refactor: remove mul method from SparseMatrix class and update mulM method

Author: jobo322

package.json

@@ -38,6 +38,7 @@
   "devDependencies": {
     "@types/node": "^22.15.21",
     "@vitest/coverage-v8": "^3.1.4",
+    "benchmark": "^2.1.4",
     "eslint": "^9.27.0",
     "eslint-config-cheminfo-typescript": "^18.0.1",
     "ml-matrix": "^6.12.1",

src/__tests__/getNonZeros.test.js

@@ -1,4 +1,5 @@
-import { SparseMatrix } from '../index';
+import { describe, it, expect } from 'vitest';
+import { SparseMatrix } from '../index.js';
 
 describe('Sparse Matrix', () => {
   it('getNonZeros', () => {

src/__tests__/matrix.test.js

@@ -156,22 +156,6 @@ export class SparseMatrix {
     return this;
   }
 
-  mul(other) {
-    if (typeof other !== 'number') {
-      throw new RangeError('the argument should be a number');
-    }
-
-    if (other === 0) {
-      return new SparseMatrix(this.rows, this.columns);
-    }
-
-    this.withEachNonZero((i, j, v) => {
-      this.set(i, j, v * other);
-    });
-
-    return this;
-  }
-
   mmul(other) {
     if (this.columns !== other.rows) {
       // eslint-disable-next-line no-console
@@ -510,10 +494,18 @@ export class SparseMatrix {
    * @returns {this}
    */
   mulM(matrix) {
-    matrix.forEachNonZero((i, j, v) => {
-      this.set(i, j, this.get(i, j) * v);
-      return v;
+    if (typeof matrix !== 'number') {
+      throw new RangeError('the argument should be a number');
+    }
+
+    if (matrix === 0) {
+      this.elements = new HashTable();
+    }
+
+    this.withEachNonZero((i, j, v) => {
+      this.set(i, j, v * matrix);
     });
+
     return this;
   }
 
@@ -1503,7 +1495,6 @@ function csrToCsc(csrMatrix, numCols) {
 
 function cooToCsr(cooMatrix, nbRows = 9) {
   const { values, columns, rows } = cooMatrix;
-  //could not be the same length
   const csrRowPtr = new Float64Array(nbRows + 1);
   const length = values.length;
   let currentRow = rows[0];