Bugs related to solver fixed & minor fixes

Author: WhiteBlackGoose

AngouriMath/Convenience/MathS.cs

@@ -14,8 +14,8 @@
  */
 
 
-
-using AngouriMath.Core;
+using System;
+using AngouriMath.Core;
 using AngouriMath.Core.FromString;
 using System.Linq.Expressions;
 using AngouriMath.Core.FromLinq;
@@ -53,6 +53,7 @@ public static EquationSystem Equations(params Entity[] equations)
         /// matrix.shape[0] - number of solutions
         /// matrix.shape[1] is equal to amount of variables
         /// </returns>
+        [ObsoleteAttribute("Use MathS.Equations instead")]
         public static Tensor Solve(List<Entity> equations, List<VariableEntity> vars)
             => EquationSolver.SolveSystem(equations, vars);
 
@@ -62,9 +63,19 @@ public static Tensor Solve(List<Entity> equations, List<VariableEntity> vars)
         /// <param name="equation"></param>
         /// <param name="var"></param>
         /// <returns></returns>
+        [ObsoleteAttribute("Use either MathS.Equations or MathS.SolveEquation or yourexpr.SolveEquation instead")]
         public static EntitySet Solve(Entity equation, VariableEntity var)
             => EquationSolver.Solve(equation, var);
 
+        /// <summary>
+        /// Solves one equation over one variable
+        /// </summary>
+        /// <param name="equation"></param>
+        /// <param name="var"></param>
+        /// <returns></returns>
+        public static EntitySet SolveEquation(Entity equation, VariableEntity var)
+            => EquationSolver.Solve(equation, var);
+
         /// <summary>
         /// https://en.wikipedia.org/wiki/Trigonometric_functions
         /// </summary>

AngouriMath/Core/Sys/EquationSystem.cs

@@ -20,6 +20,7 @@
 using System.Linq;
 using System.Text;
 using AngouriMath.Core.Sys.Interfaces;
+using AngouriMath.Functions.Algebra.Solver;
 
 namespace AngouriMath.Core.Sys
 {
@@ -47,7 +48,7 @@ public EquationSystem(params Entity[] equations)
         /// </param>
         /// <returns></returns>
         public Tensor Solve(params VariableEntity[] vars)
-        => MathS.Solve(equations, vars.ToList());
+        => EquationSolver.SolveSystem(equations, vars.ToList());
 
         /// <summary>
         /// Returns latexised version of the system

AngouriMath/Functions/Algebra/Solver/Analytical/AnalyticalSolver.cs

@@ -315,7 +315,7 @@ EntitySet GetNotNullEntites(EntitySet set)
                         return GetNotNullEntites(FindInvertExpression(a, MathS.Pow(b, value), x));
                     else
                         // log(a, x) = value => a = x ^ value => x = a ^ (1 / value)
-                        return GetNotNullEntites(FindInvertExpression(a, 1 / MathS.Pow(b, value), x));
+                        return GetNotNullEntites(FindInvertExpression(b, MathS.Pow(a, 1 / value), x));
                 default:
                     throw new SysException("Unknown function");
             }
@@ -424,7 +424,7 @@ internal static void Solve(Entity expr, VariableEntity x, EntitySet dst, bool co
                     continue;
                 var newExpr = replacement.Item2.DeepCopy();
                 TreeAnalyzer.FindAndReplace(ref newExpr, replacement.Item1, newVar);
-                solutions = newExpr.Solve(newVar);
+                solutions = newExpr.SolveEquation(newVar);
                 if (solutions.Count > 0/* && !newExpr.Children.Any(c => c == newVar)*/)
                 {
                     bestReplacement = replacement.Item1;
@@ -440,7 +440,7 @@ internal static void Solve(Entity expr, VariableEntity x, EntitySet dst, bool co
                 foreach (var solution in solutions)
                 {
                     var str = bestReplacement.ToString();
-                    if (bestReplacement - solution != expr)
+                        if (!compensateSolving || bestReplacement - solution != expr)
                         Solve(bestReplacement - solution, x, newDst, compensateSolving: true);
                 }
                 dst.AddRange(newDst);

Samples/Samples/Program.cs

@@ -253,10 +253,8 @@ Entity __c_min(Number val, int depth)
 
         static void Main(string[] _)
         {
-            Entity a = MathS.Vector(2, 3, 4);
-            Entity b = MathS.Vector(5, 6, 7);
-            if (a.IsTensoric() && b.IsTensoric())
-                Console.WriteLine(MathS.ScalarProduct(a as Tensor, b as Tensor));
+            Entity eqs = "x^y-3";
+            Console.WriteLine(eqs.SolveEquation("y"));
             /*
             Entity expr = "32 + x";
             var q = new List<Entity>();

Tests/UnitTests/Algebra/SolveTest.cs

@@ -342,7 +342,8 @@ public void TestInvertSin()
 
         public void AssertSystemSolvable(List<Entity> equations, List<VariableEntity> vars, int rootCount = -1)
         {
-            var sol = MathS.Solve(equations, vars);
+            var sys = MathS.Equations(equations.ToArray());
+            var sol = sys.Solve(vars.ToArray());
             Assert.IsTrue(sol.Shape[0] == rootCount || rootCount == -1, "Got " + sol.Shape[0] + " instead of " + rootCount);
             for (int i = 0; i < sol.Shape[0]; i++)
             {
@@ -431,6 +432,15 @@ public void TestTrigSystem4()
             );
             AssertSystemSolvable(eqs, VA("a", "b"), 0);
         }
+
+        [TestMethod]
+        public void TestLogs()
+        {
+            Entity eqs = "log(32, x) - 5";
+            var roots = eqs.SolveEquation("x");
+            Assert.IsTrue(roots.Count == 1);
+            AssertRoots(eqs, "x", roots[0]);
+        }
     }
 }