C grid interpolation for VectorFields - #2152

Merged
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation
Sep 9, 2025
Merged

C grid interpolation for VectorFields#2152
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation

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This PR implements C-grid interpolation for VectorFields (and Tracer Fields), building on #2122 (which will need to be merged into v4-dev first)

  • Chose the correct base branch (main for v3 changes, v4-dev for v4 changes)
  • Added tests

Using correct mesh_type and conversion
Also had to change the yi-indexing. To explore why!
Comment threadparcels/tools/interpolation_utils.py Outdated
dxdeta = np.dot(px, dphideta)
dydxsi = np.dot(py, dphidxsi)
dydeta = np.dot(py, dphideta)
dxdxsi = np.dot(dphidxsi, px)

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@erikvansebille, following up on our discussion about these four $n \times n$ matrices, and the possible memory usage that may incur for large particle sets, I think the following code can work (and reduce any need to sparse)

dxdxsi_diag=np.einsum('ij,ji->i', dphidxsi, px)
dxdeta_diag=np.einsum('ij,ji->i', dphideta, px)
dydxsi_diag=np.einsum('ij,ji->i', dphidxsi, py)
dydeta_diag=np.einsum('ij,ji->i', dphideta, py)
jac_diag=dxdxsi_diag*dydeta_diag-dxdeta_diag*dydxsi_diagreturnjac_diag

Base automatically changed from vectorized-kernel to v4-devAugust 19, 2025 18:26

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Still need to have a proper look at application_kernels/interpolation.py

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Do we have any tests that test C-grid vs A grid interpolation?

Comment on lines +86 to +90
with np.errstate(divide="ignore", invalid="ignore"):
det = np.where(det2 > 0, np.sqrt(det2), eta)

eta = np.where(abs(aa) < 1e-12, -cc / bb, np.where(det2 > 0, (-bb + det) / (2 * aa), eta))

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Which scenarios would produce the errors in particular are we ignoring here? And is the rest of the code robust to the nans/inf values that ignoring the errors would produce?

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The way that np.where works is that it always computes both the True and False results (as far as I understand).
That means that it will for example take the np.sqrt(det2) even if det2 < 0, leading to a lot of warnings (have you not seen them in your test results?).
The with np.errstate() filters these warnings out
So yes, the code is robust to NaNs and Infs, because these would not be warnings but errors

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one option would be to do:

mask=det2>0det[mask] =np.sqrt(det2[mask])

lets just merge for now and leave this 'unresolved' in the PR - minor thing

Comment threadparcels/xgrid.py Outdated
Comment threadparcels/field.py Outdated
Comment threadtests/v4/test_field.py
Comment threadparcels/application_kernels/interpolation.py
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels v4 releaseSep 8, 2025
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels developmentSep 8, 2025
@erikvansebille
erikvansebille merged commit 1c8d5e5 into v4-devSep 9, 2025
8 of 9 checks passed
@erikvansebille
erikvansebille deleted the c-grid-interpolation branch September 9, 2025 13:26
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels v4 releaseSep 9, 2025
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}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
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C grid interpolation for VectorFields - #2152

Merged
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation
Sep 9, 2025
Merged

C grid interpolation for VectorFields#2152
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation

Conversation

@erikvansebille

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This PR implements C-grid interpolation for VectorFields (and Tracer Fields), building on #2122 (which will need to be merged into v4-dev first)

  • Chose the correct base branch (main for v3 changes, v4-dev for v4 changes)
  • Added tests

Using correct mesh_type and conversion
Also had to change the yi-indexing. To explore why!
Comment threadparcels/tools/interpolation_utils.py Outdated
dxdeta = np.dot(px, dphideta)
dydxsi = np.dot(py, dphidxsi)
dydeta = np.dot(py, dphideta)
dxdxsi = np.dot(dphidxsi, px)

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Member

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@erikvansebille, following up on our discussion about these four $n \times n$ matrices, and the possible memory usage that may incur for large particle sets, I think the following code can work (and reduce any need to sparse)

dxdxsi_diag=np.einsum('ij,ji->i', dphidxsi, px)
dxdeta_diag=np.einsum('ij,ji->i', dphideta, px)
dydxsi_diag=np.einsum('ij,ji->i', dphidxsi, py)
dydeta_diag=np.einsum('ij,ji->i', dphideta, py)
jac_diag=dxdxsi_diag*dydeta_diag-dxdeta_diag*dydxsi_diagreturnjac_diag

Base automatically changed from vectorized-kernel to v4-devAugust 19, 2025 18:26

@VeckoTheGeckoVeckoTheGecko left a comment

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Still need to have a proper look at application_kernels/interpolation.py

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Do we have any tests that test C-grid vs A grid interpolation?

Comment on lines +86 to +90
with np.errstate(divide="ignore", invalid="ignore"):
det = np.where(det2 > 0, np.sqrt(det2), eta)

eta = np.where(abs(aa) < 1e-12, -cc / bb, np.where(det2 > 0, (-bb + det) / (2 * aa), eta))

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Which scenarios would produce the errors in particular are we ignoring here? And is the rest of the code robust to the nans/inf values that ignoring the errors would produce?

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MemberAuthor

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The way that np.where works is that it always computes both the True and False results (as far as I understand).
That means that it will for example take the np.sqrt(det2) even if det2 < 0, leading to a lot of warnings (have you not seen them in your test results?).
The with np.errstate() filters these warnings out
So yes, the code is robust to NaNs and Infs, because these would not be warnings but errors

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one option would be to do:

mask=det2>0det[mask] =np.sqrt(det2[mask])

lets just merge for now and leave this 'unresolved' in the PR - minor thing

Comment threadparcels/xgrid.py Outdated
Comment threadparcels/field.py Outdated
Comment threadtests/v4/test_field.py
Comment threadparcels/application_kernels/interpolation.py
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels v4 releaseSep 8, 2025
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels developmentSep 8, 2025
@erikvansebille
erikvansebille merged commit 1c8d5e5 into v4-devSep 9, 2025
8 of 9 checks passed
@erikvansebille
erikvansebille deleted the c-grid-interpolation branch September 9, 2025 13:26
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels v4 releaseSep 9, 2025
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels developmentSep 9, 2025
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@erikvansebille@michaeldenes@VeckoTheGecko
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix"); } } catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
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C grid interpolation for VectorFields - #2152

Merged
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation
Sep 9, 2025
Merged

C grid interpolation for VectorFields#2152
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation

Conversation

@erikvansebille

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This PR implements C-grid interpolation for VectorFields (and Tracer Fields), building on #2122 (which will need to be merged into v4-dev first)

  • Chose the correct base branch (main for v3 changes, v4-dev for v4 changes)
  • Added tests

Using correct mesh_type and conversion
Also had to change the yi-indexing. To explore why!
Comment threadparcels/tools/interpolation_utils.py Outdated
dxdeta = np.dot(px, dphideta)
dydxsi = np.dot(py, dphidxsi)
dydeta = np.dot(py, dphideta)
dxdxsi = np.dot(dphidxsi, px)

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@erikvansebille, following up on our discussion about these four $n \times n$ matrices, and the possible memory usage that may incur for large particle sets, I think the following code can work (and reduce any need to sparse)

dxdxsi_diag=np.einsum('ij,ji->i', dphidxsi, px)
dxdeta_diag=np.einsum('ij,ji->i', dphideta, px)
dydxsi_diag=np.einsum('ij,ji->i', dphidxsi, py)
dydeta_diag=np.einsum('ij,ji->i', dphideta, py)
jac_diag=dxdxsi_diag*dydeta_diag-dxdeta_diag*dydxsi_diagreturnjac_diag

Base automatically changed from vectorized-kernel to v4-devAugust 19, 2025 18:26

@VeckoTheGeckoVeckoTheGecko left a comment

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Still need to have a proper look at application_kernels/interpolation.py

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Do we have any tests that test C-grid vs A grid interpolation?

Comment on lines +86 to +90
with np.errstate(divide="ignore", invalid="ignore"):
det = np.where(det2 > 0, np.sqrt(det2), eta)

eta = np.where(abs(aa) < 1e-12, -cc / bb, np.where(det2 > 0, (-bb + det) / (2 * aa), eta))

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Which scenarios would produce the errors in particular are we ignoring here? And is the rest of the code robust to the nans/inf values that ignoring the errors would produce?

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MemberAuthor

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The way that np.where works is that it always computes both the True and False results (as far as I understand).
That means that it will for example take the np.sqrt(det2) even if det2 < 0, leading to a lot of warnings (have you not seen them in your test results?).
The with np.errstate() filters these warnings out
So yes, the code is robust to NaNs and Infs, because these would not be warnings but errors

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one option would be to do:

mask=det2>0det[mask] =np.sqrt(det2[mask])

lets just merge for now and leave this 'unresolved' in the PR - minor thing

Comment threadparcels/xgrid.py Outdated
Comment threadparcels/field.py Outdated
Comment threadtests/v4/test_field.py
Comment threadparcels/application_kernels/interpolation.py
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels v4 releaseSep 8, 2025
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels developmentSep 8, 2025
@erikvansebille
erikvansebille merged commit 1c8d5e5 into v4-devSep 9, 2025
8 of 9 checks passed
@erikvansebille
erikvansebille deleted the c-grid-interpolation branch September 9, 2025 13:26
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels v4 releaseSep 9, 2025
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels developmentSep 9, 2025
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms"); } } catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
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C grid interpolation for VectorFields - #2152

Merged
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation
Sep 9, 2025
Merged

C grid interpolation for VectorFields#2152
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation

Conversation

@erikvansebille

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This PR implements C-grid interpolation for VectorFields (and Tracer Fields), building on #2122 (which will need to be merged into v4-dev first)

  • Chose the correct base branch (main for v3 changes, v4-dev for v4 changes)
  • Added tests

Using correct mesh_type and conversion
Also had to change the yi-indexing. To explore why!
Comment threadparcels/tools/interpolation_utils.py Outdated
dxdeta = np.dot(px, dphideta)
dydxsi = np.dot(py, dphidxsi)
dydeta = np.dot(py, dphideta)
dxdxsi = np.dot(dphidxsi, px)

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Member

Choose a reason for hiding this comment

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@erikvansebille, following up on our discussion about these four $n \times n$ matrices, and the possible memory usage that may incur for large particle sets, I think the following code can work (and reduce any need to sparse)

dxdxsi_diag=np.einsum('ij,ji->i', dphidxsi, px)
dxdeta_diag=np.einsum('ij,ji->i', dphideta, px)
dydxsi_diag=np.einsum('ij,ji->i', dphidxsi, py)
dydeta_diag=np.einsum('ij,ji->i', dphideta, py)
jac_diag=dxdxsi_diag*dydeta_diag-dxdeta_diag*dydxsi_diagreturnjac_diag

Base automatically changed from vectorized-kernel to v4-devAugust 19, 2025 18:26

@VeckoTheGeckoVeckoTheGecko left a comment

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Still need to have a proper look at application_kernels/interpolation.py

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Do we have any tests that test C-grid vs A grid interpolation?

Comment on lines +86 to +90
with np.errstate(divide="ignore", invalid="ignore"):
det = np.where(det2 > 0, np.sqrt(det2), eta)

eta = np.where(abs(aa) < 1e-12, -cc / bb, np.where(det2 > 0, (-bb + det) / (2 * aa), eta))

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Which scenarios would produce the errors in particular are we ignoring here? And is the rest of the code robust to the nans/inf values that ignoring the errors would produce?

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MemberAuthor

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The way that np.where works is that it always computes both the True and False results (as far as I understand).
That means that it will for example take the np.sqrt(det2) even if det2 < 0, leading to a lot of warnings (have you not seen them in your test results?).
The with np.errstate() filters these warnings out
So yes, the code is robust to NaNs and Infs, because these would not be warnings but errors

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one option would be to do:

mask=det2>0det[mask] =np.sqrt(det2[mask])

lets just merge for now and leave this 'unresolved' in the PR - minor thing

Comment threadparcels/xgrid.py Outdated
Comment threadparcels/field.py Outdated
Comment threadtests/v4/test_field.py
Comment threadparcels/application_kernels/interpolation.py
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels v4 releaseSep 8, 2025
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels developmentSep 8, 2025
@erikvansebille
erikvansebille merged commit 1c8d5e5 into v4-devSep 9, 2025
8 of 9 checks passed
@erikvansebille
erikvansebille deleted the c-grid-interpolation branch September 9, 2025 13:26
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels v4 releaseSep 9, 2025
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels developmentSep 9, 2025
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@erikvansebille@michaeldenes@VeckoTheGecko
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links"); } } catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); } })(); (function(){ try { var __m = "youtube.com"; var __re = new RegExp('^' + "youtube\\.com" + '
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C grid interpolation for VectorFields - #2152

Merged
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation
Sep 9, 2025
Merged

C grid interpolation for VectorFields#2152
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation

Conversation

@erikvansebille

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This PR implements C-grid interpolation for VectorFields (and Tracer Fields), building on #2122 (which will need to be merged into v4-dev first)

  • Chose the correct base branch (main for v3 changes, v4-dev for v4 changes)
  • Added tests

Using correct mesh_type and conversion
Also had to change the yi-indexing. To explore why!
Comment threadparcels/tools/interpolation_utils.py Outdated
dxdeta = np.dot(px, dphideta)
dydxsi = np.dot(py, dphidxsi)
dydeta = np.dot(py, dphideta)
dxdxsi = np.dot(dphidxsi, px)

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@erikvansebille, following up on our discussion about these four $n \times n$ matrices, and the possible memory usage that may incur for large particle sets, I think the following code can work (and reduce any need to sparse)

dxdxsi_diag=np.einsum('ij,ji->i', dphidxsi, px)
dxdeta_diag=np.einsum('ij,ji->i', dphideta, px)
dydxsi_diag=np.einsum('ij,ji->i', dphidxsi, py)
dydeta_diag=np.einsum('ij,ji->i', dphideta, py)
jac_diag=dxdxsi_diag*dydeta_diag-dxdeta_diag*dydxsi_diagreturnjac_diag

Base automatically changed from vectorized-kernel to v4-devAugust 19, 2025 18:26

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Still need to have a proper look at application_kernels/interpolation.py

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Do we have any tests that test C-grid vs A grid interpolation?

Comment on lines +86 to +90
with np.errstate(divide="ignore", invalid="ignore"):
det = np.where(det2 > 0, np.sqrt(det2), eta)

eta = np.where(abs(aa) < 1e-12, -cc / bb, np.where(det2 > 0, (-bb + det) / (2 * aa), eta))

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Which scenarios would produce the errors in particular are we ignoring here? And is the rest of the code robust to the nans/inf values that ignoring the errors would produce?

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The way that np.where works is that it always computes both the True and False results (as far as I understand).
That means that it will for example take the np.sqrt(det2) even if det2 < 0, leading to a lot of warnings (have you not seen them in your test results?).
The with np.errstate() filters these warnings out
So yes, the code is robust to NaNs and Infs, because these would not be warnings but errors

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one option would be to do:

mask=det2>0det[mask] =np.sqrt(det2[mask])

lets just merge for now and leave this 'unresolved' in the PR - minor thing

Comment threadparcels/xgrid.py Outdated
Comment threadparcels/field.py Outdated
Comment threadtests/v4/test_field.py
Comment threadparcels/application_kernels/interpolation.py
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels v4 releaseSep 8, 2025
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels developmentSep 8, 2025
@erikvansebille
erikvansebille merged commit 1c8d5e5 into v4-devSep 9, 2025
8 of 9 checks passed
@erikvansebille
erikvansebille deleted the c-grid-interpolation branch September 9, 2025 13:26
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels v4 releaseSep 9, 2025
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels developmentSep 9, 2025
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default"); } } catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
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C grid interpolation for VectorFields - #2152

Merged
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation
Sep 9, 2025
Merged

C grid interpolation for VectorFields#2152
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation

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This PR implements C-grid interpolation for VectorFields (and Tracer Fields), building on #2122 (which will need to be merged into v4-dev first)

  • Chose the correct base branch (main for v3 changes, v4-dev for v4 changes)
  • Added tests

Using correct mesh_type and conversion
Also had to change the yi-indexing. To explore why!
Comment threadparcels/tools/interpolation_utils.py Outdated
dxdeta = np.dot(px, dphideta)
dydxsi = np.dot(py, dphidxsi)
dydeta = np.dot(py, dphideta)
dxdxsi = np.dot(dphidxsi, px)

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@erikvansebille, following up on our discussion about these four $n \times n$ matrices, and the possible memory usage that may incur for large particle sets, I think the following code can work (and reduce any need to sparse)

dxdxsi_diag=np.einsum('ij,ji->i', dphidxsi, px)
dxdeta_diag=np.einsum('ij,ji->i', dphideta, px)
dydxsi_diag=np.einsum('ij,ji->i', dphidxsi, py)
dydeta_diag=np.einsum('ij,ji->i', dphideta, py)
jac_diag=dxdxsi_diag*dydeta_diag-dxdeta_diag*dydxsi_diagreturnjac_diag

Base automatically changed from vectorized-kernel to v4-devAugust 19, 2025 18:26

@VeckoTheGeckoVeckoTheGecko left a comment

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Still need to have a proper look at application_kernels/interpolation.py

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Do we have any tests that test C-grid vs A grid interpolation?

Comment on lines +86 to +90
with np.errstate(divide="ignore", invalid="ignore"):
det = np.where(det2 > 0, np.sqrt(det2), eta)

eta = np.where(abs(aa) < 1e-12, -cc / bb, np.where(det2 > 0, (-bb + det) / (2 * aa), eta))

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Which scenarios would produce the errors in particular are we ignoring here? And is the rest of the code robust to the nans/inf values that ignoring the errors would produce?

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The way that np.where works is that it always computes both the True and False results (as far as I understand).
That means that it will for example take the np.sqrt(det2) even if det2 < 0, leading to a lot of warnings (have you not seen them in your test results?).
The with np.errstate() filters these warnings out
So yes, the code is robust to NaNs and Infs, because these would not be warnings but errors

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one option would be to do:

mask=det2>0det[mask] =np.sqrt(det2[mask])

lets just merge for now and leave this 'unresolved' in the PR - minor thing

Comment threadparcels/xgrid.py Outdated
Comment threadparcels/field.py Outdated
Comment threadtests/v4/test_field.py
Comment threadparcels/application_kernels/interpolation.py
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels v4 releaseSep 8, 2025
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels developmentSep 8, 2025
@erikvansebille
erikvansebille merged commit 1c8d5e5 into v4-devSep 9, 2025
8 of 9 checks passed
@erikvansebille
erikvansebille deleted the c-grid-interpolation branch September 9, 2025 13:26
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels v4 releaseSep 9, 2025
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels developmentSep 9, 2025
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers"); } } catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
Skip to content

C grid interpolation for VectorFields - #2152

Merged
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation
Sep 9, 2025
Merged

C grid interpolation for VectorFields#2152
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation

Conversation

@erikvansebille

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This PR implements C-grid interpolation for VectorFields (and Tracer Fields), building on #2122 (which will need to be merged into v4-dev first)

  • Chose the correct base branch (main for v3 changes, v4-dev for v4 changes)
  • Added tests

Using correct mesh_type and conversion
Also had to change the yi-indexing. To explore why!
Comment threadparcels/tools/interpolation_utils.py Outdated
dxdeta = np.dot(px, dphideta)
dydxsi = np.dot(py, dphidxsi)
dydeta = np.dot(py, dphideta)
dxdxsi = np.dot(dphidxsi, px)

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@erikvansebille, following up on our discussion about these four $n \times n$ matrices, and the possible memory usage that may incur for large particle sets, I think the following code can work (and reduce any need to sparse)

dxdxsi_diag=np.einsum('ij,ji->i', dphidxsi, px)
dxdeta_diag=np.einsum('ij,ji->i', dphideta, px)
dydxsi_diag=np.einsum('ij,ji->i', dphidxsi, py)
dydeta_diag=np.einsum('ij,ji->i', dphideta, py)
jac_diag=dxdxsi_diag*dydeta_diag-dxdeta_diag*dydxsi_diagreturnjac_diag

Base automatically changed from vectorized-kernel to v4-devAugust 19, 2025 18:26

@VeckoTheGeckoVeckoTheGecko left a comment

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Still need to have a proper look at application_kernels/interpolation.py

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Do we have any tests that test C-grid vs A grid interpolation?

Comment on lines +86 to +90
with np.errstate(divide="ignore", invalid="ignore"):
det = np.where(det2 > 0, np.sqrt(det2), eta)

eta = np.where(abs(aa) < 1e-12, -cc / bb, np.where(det2 > 0, (-bb + det) / (2 * aa), eta))

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Which scenarios would produce the errors in particular are we ignoring here? And is the rest of the code robust to the nans/inf values that ignoring the errors would produce?

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MemberAuthor

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The way that np.where works is that it always computes both the True and False results (as far as I understand).
That means that it will for example take the np.sqrt(det2) even if det2 < 0, leading to a lot of warnings (have you not seen them in your test results?).
The with np.errstate() filters these warnings out
So yes, the code is robust to NaNs and Infs, because these would not be warnings but errors

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one option would be to do:

mask=det2>0det[mask] =np.sqrt(det2[mask])

lets just merge for now and leave this 'unresolved' in the PR - minor thing

Comment threadparcels/xgrid.py Outdated
Comment threadparcels/field.py Outdated
Comment threadtests/v4/test_field.py
Comment threadparcels/application_kernels/interpolation.py
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels v4 releaseSep 8, 2025
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels developmentSep 8, 2025
@erikvansebille
erikvansebille merged commit 1c8d5e5 into v4-devSep 9, 2025
8 of 9 checks passed
@erikvansebille
erikvansebille deleted the c-grid-interpolation branch September 9, 2025 13:26
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels v4 releaseSep 9, 2025
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels developmentSep 9, 2025
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3 participants

@erikvansebille@michaeldenes@VeckoTheGecko
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode"); } } catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); } })(); })();
Skip to content

C grid interpolation for VectorFields - #2152

Merged
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation
Sep 9, 2025
Merged

C grid interpolation for VectorFields#2152
erikvansebille merged 38 commits into
v4-devfrom
c-grid-interpolation

Conversation

@erikvansebille

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This PR implements C-grid interpolation for VectorFields (and Tracer Fields), building on #2122 (which will need to be merged into v4-dev first)

  • Chose the correct base branch (main for v3 changes, v4-dev for v4 changes)
  • Added tests

Using correct mesh_type and conversion
Also had to change the yi-indexing. To explore why!
Comment threadparcels/tools/interpolation_utils.py Outdated
dxdeta = np.dot(px, dphideta)
dydxsi = np.dot(py, dphidxsi)
dydeta = np.dot(py, dphideta)
dxdxsi = np.dot(dphidxsi, px)

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@erikvansebille, following up on our discussion about these four $n \times n$ matrices, and the possible memory usage that may incur for large particle sets, I think the following code can work (and reduce any need to sparse)

dxdxsi_diag=np.einsum('ij,ji->i', dphidxsi, px)
dxdeta_diag=np.einsum('ij,ji->i', dphideta, px)
dydxsi_diag=np.einsum('ij,ji->i', dphidxsi, py)
dydeta_diag=np.einsum('ij,ji->i', dphideta, py)
jac_diag=dxdxsi_diag*dydeta_diag-dxdeta_diag*dydxsi_diagreturnjac_diag

Base automatically changed from vectorized-kernel to v4-devAugust 19, 2025 18:26

@VeckoTheGeckoVeckoTheGecko left a comment

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Still need to have a proper look at application_kernels/interpolation.py

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Do we have any tests that test C-grid vs A grid interpolation?

Comment on lines +86 to +90
with np.errstate(divide="ignore", invalid="ignore"):
det = np.where(det2 > 0, np.sqrt(det2), eta)

eta = np.where(abs(aa) < 1e-12, -cc / bb, np.where(det2 > 0, (-bb + det) / (2 * aa), eta))

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Which scenarios would produce the errors in particular are we ignoring here? And is the rest of the code robust to the nans/inf values that ignoring the errors would produce?

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MemberAuthor

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The way that np.where works is that it always computes both the True and False results (as far as I understand).
That means that it will for example take the np.sqrt(det2) even if det2 < 0, leading to a lot of warnings (have you not seen them in your test results?).
The with np.errstate() filters these warnings out
So yes, the code is robust to NaNs and Infs, because these would not be warnings but errors

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one option would be to do:

mask=det2>0det[mask] =np.sqrt(det2[mask])

lets just merge for now and leave this 'unresolved' in the PR - minor thing

Comment threadparcels/xgrid.py Outdated
Comment threadparcels/field.py Outdated
Comment threadtests/v4/test_field.py
Comment threadparcels/application_kernels/interpolation.py
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels v4 releaseSep 8, 2025
@github-project-automationgithub-project-automationBot moved this from Backlog to Ready in Parcels developmentSep 8, 2025
@erikvansebille
erikvansebille merged commit 1c8d5e5 into v4-devSep 9, 2025
8 of 9 checks passed
@erikvansebille
erikvansebille deleted the c-grid-interpolation branch September 9, 2025 13:26
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels v4 releaseSep 9, 2025
@github-project-automationgithub-project-automationBot moved this from Ready to Done in Parcels developmentSep 9, 2025
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