fix: #2960 add type definition of function symbolicEqual (#3035)

types/index.d.ts

@@ -2448,6 +2448,21 @@ declare namespace math {
       y: MathType | string
     ): boolean | MathCollection
 
+    /**
+     * Determines if two expressions are symbolically equal, i.e. one is the
+     * result of valid algebraic manipulations on the other.
+     * @param {Node|string} expr1 The first expression to compare
+     * @param {Node|string} expr2 The second expression to compare
+     * @param {Object} [options] Optional option object, passed to simplify
+     * @returns {boolean} Returns true if a valid manipulation making the
+     * expressions equal is found.
+     */
+    symbolicEqual(
+      expr1: MathNode | string,
+      expr2: MathNode | string,
+      options?: SimplifyOptions
+    ): boolean
+
     /**
      * Test whether two values are unequal. The function tests whether the
      * relative difference between x and y is larger than the configured
@@ -5843,6 +5858,21 @@ declare namespace math {
       y: MathType | string
     ): MathJsChain<boolean | MathCollection>
 
+    /**
+     * Determines if two expressions are symbolically equal, i.e. one is the
+     * result of valid algebraic manipulations on the other.
+     * @param {Node|string} expr1 The first expression to compare
+     * @param {Node|string} expr2 The second expression to compare
+     * @param {Object} [options] Optional option object, passed to simplify
+     * @returns {boolean} Returns true if a valid manipulation making the
+     * expressions equal is found.
+     */
+    symbolicEqual(
+      this: MathJsChain<MathNode | string>,
+      expr2: MathNode | string,
+      options?: SimplifyOptions
+    ): boolean
+
     /**
      * Test whether two values are unequal. The function tests whether the
      * relative difference between x and y is larger than the configured