Add `ifail` `enum` by chris-ashe · Pull Request #4275 · ukaea/PROCESS

chris-ashe · 2026-05-27T15:19:59Z

Description

Checklist

I confirm that I have completed the following checks:

My changes follow the PROCESS style guide
I have justified any large differences in the regression tests caused by this pull request in the comments.
I have added new tests where appropriate for the changes I have made.
If I have had to change any existing unit or integration tests, I have justified this change in the pull request comments.
If I have made documentation changes, I have checked they render correctly.
I have added documentation for my change, if appropriate.

codecov-commenter · 2026-05-27T15:30:07Z

Codecov Report

❌ Patch coverage is 47.82609% with 24 lines in your changes missing coverage. Please review.
✅ Project coverage is 49.30%. Comparing base (bd4752b) to head (1647e75).

Files with missing lines	Patch %	Lines
process/core/scan.py	10.00%	9 Missing ⚠️
process/core/solver/solver.py	42.85%	4 Missing ⚠️
process/core/io/vary_run/tools.py	25.00%	3 Missing ⚠️
process/core/solver/solver_handler.py	25.00%	3 Missing ⚠️
process/core/io/plot/scans.py	33.33%	2 Missing ⚠️
process/core/io/vary_run/config.py	33.33%	2 Missing ⚠️
process/core/final.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4275      +/-   ##
==========================================
+ Coverage   49.24%   49.30%   +0.06%     
==========================================
  Files         151      151              
  Lines       29611    29611              
==========================================
+ Hits        14581    14599      +18     
+ Misses      15030    15012      -18

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Copilot

Pull request overview

This PR introduces a typed IntEnum for solver ifail exit conditions (SolverOutputCondition) and updates several runtime and test call sites to use the enum instead of hard-coded numeric values, improving readability and consistency around solver status handling.

Changes:

Added SolverOutputCondition enum to centralize solver output (ifail) codes.
Replaced ifail == 1 / ifail != 1 checks with SolverOutputCondition.CONVERGED in core, tracking, and vary-run utilities.
Updated regression/integration tests to assert against the enum values.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tracking/tracking_data.py	Uses `SolverOutputCondition.CONVERGED` for strict convergence checks when reading MFILEs.
tests/regression/test_process_input_files.py	Updates regression assertion to use `SolverOutputCondition.CONVERGED`.
tests/integration/test_vmcon.py	Replaces numeric `ifail` expectations with enum values.
process/data_structure/numerics.py	Adds the new `SolverOutputCondition` `IntEnum` definition.
process/core/solver/solver_handler.py	Uses enum values in VMCON retry logic and imports the enum.
process/core/scan.py	Uses enum values in optimisation/solver status reporting and VMCON error handling.
process/core/io/vary_run/tools.py	Uses enum values when determining feasibility/convergence from MFILE contents.
process/core/io/vary_run/config.py	Uses enum values to report convergence status and generate README status messages.
process/core/final.py	Uses enum value for final feasible/unfeasible output header selection.

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@@ -73,7 +74,7 @@ def run(self):
                # to next attempt


+class SolverOutputCondition(IntEnum):
+    """Enum for the possible conditions that can be returned by the solvers.
+    This is for the `ifail` condition
+    """


+    IMPROPER_INPUT = 0
+    """Solver failed due to improper input (e.g. invalid parameters, or failure to
+    satisfy solver preconditions)"""
+    CONVERGED = 1
+    """Solver converged successfully"""
+
+    MAX_ITERATIONS = 2
+    """Solver failed to converge within the maximum number of iterations"""
+
+    MAX_LINE_SEARCHES = 3
+    """Line search required 10 function calls without finding a better solution"""
+
+    UPHILL_SEARCH = 4
+    """Uphill search direction was calculated"""
+
+    NO_SOLUTION = 5
+    """No feasible solution or bad approximation of Hessian"""
+
+    SINGLE_MATRIX_OR_BOUNDS = 6
+    """Singular matrix in quadratic subproblem or restriction by artificial bounds"""


clmould

Some docs points:

Can the SolverOutputCondition enum be included in the vmcon page in the docs, eg something like

a brief sentence to say that the ifail values are now contained in this enum
an extra column in the ifail table to link the ifail values to the enum

Also the troubleshooting docs page mentions ifail = 3 - think it'd be worth adding a reference to the the enum for this value and adding a brief description of what this means here

timothy-nunn · 2026-06-24T10:45:21Z

+    MAX_LINE_SEARCHES = 3
+    """Line search required 10 function calls without finding a better solution"""
+
+    UPHILL_SEARCH = 4
+    """Uphill search direction was calculated"""


Might be worth noting that these are solver specific and won't always be raised (e.g. using fsolve or some custom solver)

timothy-nunn

This method should be typed to return the enum

PROCESS/process/core/solver/solver.py

Line 131 in b211d2c

def solve(self) -> int:
The same with the VMCON solve method. I would then also update the setting of self.info in this method to use the enum:

PROCESS/process/core/solver/solver.py

Line 173 in b211d2c

def solve(self) -> int:
You can probably remove all references to UPHILL_SEARCH because it is not used anymore as far as I can tell

timothy-nunn · 2026-07-14T08:00:05Z

+    MAX_LINE_SEARCHES = 3
+    # Line search required 10 function calls without finding a better solution


This one is solver specific, most solvers do not have an integrated line search

clmould

A few suggested changes, plus a couple other things:

Can Tim's review comments be addressed too please
Can troubleshooting.md also reference the SolverOutputCondition here please:

eg something like ... error code `ifail = 3` (`SolverOutputCondition.MAX_LINE_SEARCHES`) is encountered ...

clmould

I'm happy now! Will wait for @timothy-nunn to check he is happy with his previous comments then will merge :)

timothy-nunn

Can we remove references to SINGULAR_MATRIX_OR_BOUNDS and UPHILL_SEARCH because:

They are solver specific
I don't think either have been used since the move to PyVMCON

…clarity and maintainability

Co-authored-by: clmould <86794332+clmould@users.noreply.github.com>

…rity and consistency

Co-authored-by: Timothy <75321887+timothy-nunn@users.noreply.github.com>

…clearer status reporting

Co-authored-by: clmould <86794332+clmould@users.noreply.github.com>

…GULAR_MATRIX_OR_BOUNDS values; update related error handling in scan.py for improved clarity.

chris-ashe added Convergence Solver or convergence-related problems Refactor labels May 27, 2026

chris-ashe marked this pull request as ready for review June 2, 2026 13:45

chris-ashe requested a review from a team as a code owner June 2, 2026 13:45

Copilot AI review requested due to automatic review settings June 2, 2026 13:45

Copilot started reviewing on behalf of chris-ashe June 2, 2026 13:45 View session

Copilot AI reviewed Jun 2, 2026

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clmould self-assigned this Jun 5, 2026

chris-ashe force-pushed the add_ifail_enum branch from 6764908 to 6396b58 Compare June 19, 2026 11:00

clmould requested changes Jun 19, 2026

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timothy-nunn reviewed Jun 24, 2026

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chris-ashe requested a review from clmould July 9, 2026 14:18

chris-ashe force-pushed the add_ifail_enum branch from ace13ef to 9e8ad48 Compare July 13, 2026 10:32

timothy-nunn requested changes Jul 14, 2026

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clmould requested changes Jul 14, 2026

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Comment thread tests/integration/test_vmcon.py Outdated

Comment thread documentation/source/solver/optsolverdoc.md Outdated

Comment thread process/core/scan.py Outdated

chris-ashe force-pushed the add_ifail_enum branch from 0f3cc80 to e3ef760 Compare July 22, 2026 09:07

chris-ashe requested a review from clmould July 22, 2026 09:14

chris-ashe force-pushed the add_ifail_enum branch from 2e74cdb to 8133217 Compare July 22, 2026 09:17

clmould requested changes Jul 22, 2026

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Comment thread process/core/solver/solver_handler.py Outdated

Comment thread process/core/solver/solver_handler.py Outdated

Comment thread process/core/scan.py Outdated

chris-ashe requested review from clmould and timothy-nunn July 28, 2026 08:51

chris-ashe force-pushed the add_ifail_enum branch from bdd6d14 to 7233770 Compare July 28, 2026 15:00

clmould approved these changes Jul 29, 2026

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timothy-nunn requested changes Jul 30, 2026

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Comment thread process/core/solver/solver.py Outdated

chris-ashe requested a review from timothy-nunn July 30, 2026 13:47

timothy-nunn approved these changes Jul 30, 2026

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chris-ashe added 2 commits July 30, 2026 15:51

Add ifail enum to define solver output conditions

3482482

Refactor ifail checks to use SolverOutputCondition enum for improved …

2b10d6f

…clarity and maintainability

chris-ashe and others added 11 commits July 30, 2026 15:52

Post rebase fixes

976894c

Update process/data_structure/numerics.py

478358d

Co-authored-by: clmould <86794332+clmould@users.noreply.github.com>

Refactor ifail handling to use SolverOutputCondition enum for cla…

3ef3b81

…rity and consistency

Refactor ifail handling to use SolverOutputCondition enum for cla…

09a085b

…rity and consistency

Post rebase pre commit fix

629bd0b

requested changes

cd5889b

Update process/data_structure/numerics.py

23f23ab

Co-authored-by: Timothy <75321887+timothy-nunn@users.noreply.github.com>

Enhance error handling by integrating SolverOutputCondition enum for …

11c4683

…clearer status reporting

Update process/core/scan.py

e695879

Co-authored-by: clmould <86794332+clmould@users.noreply.github.com>

Refactor SolverOutputCondition enum by removing UPHILL_SEARCH and SIN…

f7690c7

…GULAR_MATRIX_OR_BOUNDS values; update related error handling in scan.py for improved clarity.

Update Vmcon solver to use SolverOutputCondition for convergence status

1647e75

chris-ashe force-pushed the add_ifail_enum branch from 8de68d9 to 1647e75 Compare July 30, 2026 14:53

timothy-nunn approved these changes Jul 30, 2026

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timothy-nunn enabled auto-merge (squash) July 30, 2026 15:39

timothy-nunn disabled auto-merge July 30, 2026 15:39

timothy-nunn merged commit bbed21c into main Jul 30, 2026
10 of 11 checks passed

timothy-nunn deleted the add_ifail_enum branch July 30, 2026 15:39

		MAX_LINE_SEARCHES = 3
		# Line search required 10 function calls without finding a better solution

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chris-ashe commented May 27, 2026

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codecov-commenter commented May 27, 2026 •

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