Add C to integration result, change integral node to support range instead of iterations, implement u-substitution and quadratic denominator integral, integration of abs(x), sgn(x) and ln(abs(x))^2 #657

Happypig375 · 2026-01-20T20:34:36Z

No description provided.

Copilot

Pull request overview

This pull request significantly refactors the integral system in AngouriMath by changing from an iteration-based API to a range-based API that distinguishes between indefinite and definite integrals. The PR adds automatic inclusion of the constant of integration (C) for indefinite integrals, implements u-substitution for integration, adds support for integrating rational functions with quadratic denominators, and implements integration of abs(x), sgn(x), and ln(abs(x))^2.

Changes:

Refactored integral API from Integral(expr, var, iterations) to Integral(expr, var) for indefinite integrals and Integral(expr, var, from, to) for definite integrals
Added automatic constant of integration (C) with unique naming when C is already present in the expression
Implemented u-substitution algorithm to handle a wide variety of composite function integrals
Added integration patterns for absolute value, signum function, ln(abs(x)), and rational functions with quadratic denominators
Updated all output formatters (ToString, LaTeX, SymPy) to handle the new integral representation

Reviewed changes

Copilot reviewed 33 out of 33 changed files in this pull request and generated 18 comments.

Show a summary per file

File	Description
Sources/Utils/Utils/AntlrPostProcessor.cs	Corrected path to ANTLR files by removing redundant directory level
Sources/Tests/UnitTests/PatternsTest/SimplifyTest.cs	Fixed test that incorrectly used Integral instead of Derivative
Sources/Tests/UnitTests/Convenience/ToSymPyTEst.cs	Updated SymPy output tests for new integral API
Sources/Tests/UnitTests/Convenience/LatexTest.cs	Updated LaTeX tests to use Derivative with negative iterations for integrals
Sources/Tests/UnitTests/Convenience/FromStringTest.cs	Updated parsing tests for new 4-argument definite integral syntax
Sources/Tests/UnitTests/Common/SubstituteTest.cs	Updated substitution tests for new integral API
Sources/Tests/UnitTests/Common/InnerSimplifyTest.cs	Added tests for abs/signum simplifications and updated integration tests to expect C constant
Sources/Tests/UnitTests/Common/CircleTest.cs	Updated stringize tests for new integral syntax
Sources/Tests/UnitTests/Common/BuiltinFunctionsAppliedTest.cs	Updated curried function tests to expect C constant
Sources/Tests/UnitTests/Calculus/IntegrationTest.cs	Extensively expanded with 250+ lines of new integration tests covering u-substitution, quadratic denominators, abs/sgn, and ln(abs(x))
Sources/Tests/UnitTests/Calculus/DerivativeTest.cs	Updated derivative of abs test to expect provided condition
Sources/Tests/FSharpWrapperUnitTests/ShortcutsTest.fs	Updated F# wrapper tests to expect C constant
Sources/Tests/FSharpWrapperUnitTests/Functions.Order.fs	Updated F# function tests to expect C constant
Sources/AngouriMath/Functions/Substitute.cs	Fixed integral substitution to handle range (from, to) properly
Sources/AngouriMath/Functions/Simplification/Patterns/Patterns.Common.cs	Moved abs/signum patterns to InnerSimplify and added division simplification patterns with provided conditions
Sources/AngouriMath/Functions/Output/ToSympy/ToSympy.Calculus.Classes.cs	Updated SymPy output for range-based integrals
Sources/AngouriMath/Functions/Output/ToString/ToString.Calculus.Classes.cs	Updated ToString for range-based integrals
Sources/AngouriMath/Functions/Output/Latex/Latex.Calculus.Classes.cs	Updated LaTeX output to render derivatives with negative iterations as integrals and definite integrals with bounds
Sources/AngouriMath/Functions/Evaluation/Evaluation.Continuous/Evaluation.Continuous.Trigonometry.Classes.cs	Added arctan evaluation for positive/negative infinity
Sources/AngouriMath/Functions/Evaluation/Evaluation.Continuous/Evaluation.Continuous.Calculus.Classes.cs	Refactored integral evaluation to use new range-based API and call Integrate methods
Sources/AngouriMath/Functions/Evaluation/Evaluation.Continuous/Evaluation.Continuous.Arithmetics.Classes.cs	Added InnerSimplify patterns for abs(abs), sgn(sgn), abs(sgn), and sgn(abs)
Sources/AngouriMath/Functions/Continuous/Solvers/EquationSolver/InvertNode.Classes.cs	Updated equation solving for new integral API
Sources/AngouriMath/Functions/Continuous/Limits/Solvers/Limit.Classes.cs	Updated limit computation for range-based integrals
Sources/AngouriMath/Functions/Continuous/Integration/Integration.Definition.cs	Refactored to separate indefinite and definite integration, added constant of integration
Sources/AngouriMath/Functions/Continuous/Integration/IntegralPatterns.cs	Added patterns for abs, sgn, ln(abs(x)), and quadratic denominators
Sources/AngouriMath/Functions/Continuous/Integration/IndefiniteIntegralSolver.cs	Refactored to return nullable results, implemented u-substitution, improved integration by parts
Sources/AngouriMath/Functions/Continuous/Differentiation.cs	Added support for negative derivative iterations converting to integrals
Sources/AngouriMath/Core/Entity/Discrete/Entity.Discrete.Classes.cs	Fixed comment typo: "state" to "states"
Sources/AngouriMath/Core/Entity/Continuous/Entity.Continuous.Calculus.Classes.cs	Changed Integralf from iterations-based to range-based with (from, to) tuple
Sources/AngouriMath/Core/Antlr/AngouriMathParser.cs	Updated parser to accept 4-argument integral for definite integrals
Sources/AngouriMath/Core/Antlr/AngouriMath.g	Updated grammar to accept 4-argument integral and updated documentation comment
Sources/AngouriMath/Convenience/MathS.cs	Updated Integral factory methods for new API and added Boolean.True/False constants
Sources/AngouriMath/Convenience/AngouriMathExtensions.cs	Added definite integral extension method and fixed spelling errors

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-01-20T21:28:37Z

Sources/AngouriMath/Functions/Output/Latex/Latex.Calculus.Classes.cs

+using GenericTensor.Core;
+using System.Linq.Expressions;


Unnecessary imports added. The using statements for GenericTensor.Core and System.Linq.Expressions are added but don't appear to be used anywhere in the file based on the diff. These should be removed to keep the code clean.

Suggested change

using GenericTensor.Core;

using System.Linq.Expressions;

Copilot · 2026-01-20T21:28:37Z

Sources/AngouriMath/Functions/Continuous/Integration/IndefiniteIntegralSolver.cs

 // Details: https://github.com/asc-community/AngouriMath/blob/master/LICENSE.md.
 // Website: https://am.angouri.org.
 //
+using HonkSharp.Fluency;


Missing using directive. The code uses HonkSharp.Fluency for the .Pipe() extension method but this dependency should be verified to exist in the project. If this is a new dependency, it should be documented or the code should be refactored to not require it.

Copilot · 2026-01-20T21:28:38Z

Sources/AngouriMath/Convenience/AngouriMathExtensions.cs

        /// </summary>
        /// <param name="str">
-        /// The expression to be parsed and integrated over <paramref name="x"/>
+        /// The expresion to be parsed and integrated


Spelling error: "expresion" should be "expression".

Copilot · 2026-01-20T21:28:39Z

Sources/AngouriMath/Functions/Continuous/Integration/IndefiniteIntegralSolver.cs

 namespace AngouriMath.Functions.Algebra
 {
    internal static class IndefiniteIntegralSolver
    {


The condition integrateByParts is passed through to recursive calls in SolveBySplittingSum but is not documented. This parameter prevents infinite recursion during integration by parts, but the purpose and behavior should be documented to help maintainers understand the control flow.

Suggested change

{

{

/// <summary>

/// Attempts to integrate an expression that is a sum by splitting it into additive terms,

/// integrating each term independently, and then summing the resulting antiderivatives.

/// </summary>

/// <param name="expr">The expression to integrate.</param>

/// <param name="x">The variable of integration.</param>

/// <param name="integrateByParts">

/// Controls whether integration by parts is allowed for this call chain. The flag is

/// passed through to recursive calls so that, once integration by parts has been applied

/// in a particular branch of the algorithm, it can be disabled for sub-expressions to

/// avoid uncontrolled or infinite recursion on similar patterns.

/// </param>

/// <returns>

/// The antiderivative of <paramref name="expr"/> with respect to <paramref name="x"/> if

/// all terms of the sum can be integrated by the underlying solver; otherwise, <c>null</c>.

/// </returns>

Copilot · 2026-01-20T21:28:39Z

Sources/AngouriMath/Convenience/AngouriMathExtensions.cs

+        /// May return an unresolved <see cref="Integralf"/> node.
+        /// </summary>
+        /// <param name="str">
+        /// The expresion to be parsed and integrated


Spelling error: "expresion" should be "expression".

Copilot · 2026-01-20T21:28:41Z

Sources/AngouriMath/Functions/Continuous/Integration/IndefiniteIntegralSolver.cs

 // Website: https://am.angouri.org.
 //
+using HonkSharp.Fluency;
+using static AngouriMath.Entity;


Missing using directive. The code uses using static AngouriMath.Entity; but then still refers to Entity.Variable, Entity.Mulf, etc. This import appears incomplete or unnecessary - either fully utilize the static import or remove it for consistency.

Suggested change

using static AngouriMath.Entity;

Copilot · 2026-01-20T21:28:42Z

Sources/Utils/Utils/AntlrPostProcessor.cs

    public static class AntlrPostProcessorReplacePublicWithInternal
    {
-        public const string ANTLR_PATH = "../AngouriMath/AngouriMath/Core/Antlr/";
+        public const string ANTLR_PATH = "../AngouriMath/Core/Antlr/";


The path has been changed from ../AngouriMath/AngouriMath/Core/Antlr/ to ../AngouriMath/Core/Antlr/. This appears to be a correction of a redundant directory level. Ensure that this path change is correct and that the build/test infrastructure can find the files at this new location.

Copilot · 2026-01-20T21:28:42Z

Sources/Tests/UnitTests/Calculus/IntegrationTest.cs

            var expr = x;

-            Assert.True((MathS.Compute.DefiniteIntegral(expr, x, 0, 1).RealPart - 1.0/2).Abs() < 0.1);
+            Assert.True((MathS.Compute.DefiniteIntegral(expr, x, 0, 1).RealPart - 1.0 / 2).Abs() < 0.1);


Call to obsolete method DefiniteIntegral.

Copilot · 2026-01-20T21:28:42Z

...uriMath/Functions/Evaluation/Evaluation.Continuous/Evaluation.Continuous.Calculus.Classes.cs

-                return changed;
-            }

+            private static Entity? ConditionallySimplified(Entity e, bool isExact) => e is Integralf i ? null : e.InnerSimplified(isExact);


This assignment to i is useless, since its value is never read.

Suggested change

private static Entity? ConditionallySimplified(Entity e, bool isExact) => e is Integralf i ? null : e.InnerSimplified(isExact);

private static Entity? ConditionallySimplified(Entity e, bool isExact) => e is Integralf ? null : e.InnerSimplified(isExact);

Copilot · 2026-01-20T21:28:42Z

Sources/AngouriMath/Core/Antlr/AngouriMathParser.cs

+				                if (_localctx.args.list.Count == 4)
+				                    _localctx.value =  MathS.Integral(_localctx.args.list[0], _localctx.args.list[1], _localctx.args.list[2], _localctx.args.list[3]);
 				                else
-				                    throw new InvalidArgumentParseException("Expected number for the third argument of integral");
+				                    _localctx.value =  MathS.Integral(_localctx.args.list[0], _localctx.args.list[1]);


Both branches of this 'if' statement write to the same variable - consider using '?' to express intent better.

Happypig375 added 5 commits January 19, 2026 16:53

Implement constant of integration

8dcdff0

u substitution and quadratic denominator

e31895c

Integrate abs and sgn

f748d73

Implement integration of ln(abs(x))^2

fdd562e

Fix F# tests

4e29b41

Happypig375 requested a review from Copilot January 20, 2026 21:22

Copilot started reviewing on behalf of Happypig375 January 20, 2026 21:22 View session

Copilot AI reviewed Jan 20, 2026

View reviewed changes

Apply AI fixes

90767b2

Happypig375 merged commit 1aaa925 into master Jan 20, 2026
24 checks passed

Happypig375 deleted the constant-of-integration branch January 20, 2026 21:42

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Add C to integration result, change integral node to support range instead of iterations, implement u-substitution and quadratic denominator integral, integration of abs(x), sgn(x) and ln(abs(x))^2 #657

Add C to integration result, change integral node to support range instead of iterations, implement u-substitution and quadratic denominator integral, integration of abs(x), sgn(x) and ln(abs(x))^2 #657

Uh oh!

Happypig375 commented Jan 20, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Copilot AI Jan 20, 2026

Uh oh!

Copilot AI Jan 20, 2026

Uh oh!

Copilot AI Jan 20, 2026

Uh oh!

Copilot AI Jan 20, 2026

Uh oh!

Copilot AI Jan 20, 2026

Uh oh!

Copilot AI Jan 20, 2026

Uh oh!

Copilot AI Jan 20, 2026

Uh oh!

Copilot AI Jan 20, 2026

Uh oh!

Copilot AI Jan 20, 2026

Uh oh!

Copilot AI Jan 20, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

-    {
+    {
+        /// <summary>
+        /// Attempts to integrate an expression that is a sum by splitting it into additive terms,
+        /// integrating each term independently, and then summing the resulting antiderivatives.
+        /// </summary>
+        /// <param name="expr">The expression to integrate.</param>
+        /// <param name="x">The variable of integration.</param>
+        /// <param name="integrateByParts">
+        /// Controls whether integration by parts is allowed for this call chain. The flag is
+        /// passed through to recursive calls so that, once integration by parts has been applied
+        /// in a particular branch of the algorithm, it can be disabled for sub-expressions to
+        /// avoid uncontrolled or infinite recursion on similar patterns.
+        /// </param>
+        /// <returns>
+        /// The antiderivative of <paramref name="expr"/> with respect to <paramref name="x"/> if
+        /// all terms of the sum can be integrated by the underlying solver; otherwise, <c>null</c>.
+        /// </returns>

	private static Entity? ConditionallySimplified(Entity e, bool isExact) => e is Integralf i ? null : e.InnerSimplified(isExact);
	private static Entity? ConditionallySimplified(Entity e, bool isExact) => e is Integralf ? null : e.InnerSimplified(isExact);

Add C to integration result, change integral node to support range instead of iterations, implement u-substitution and quadratic denominator integral, integration of abs(x), sgn(x) and ln(abs(x))^2 #657

Add C to integration result, change integral node to support range instead of iterations, implement u-substitution and quadratic denominator integral, integration of abs(x), sgn(x) and ln(abs(x))^2 #657

Uh oh!

Conversation

Happypig375 commented Jan 20, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Copilot AI Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants