Modular Inverse: Fix modular bugs

src/algorithms/math/modular_inverse.js

@@ -1,33 +1,44 @@
 const exEuclidean = require('./extended_euclidean');
 const fastExp = require('./fast_exp');
 
+
 /**
- * Calculates modular inverse of a number
+ * Calculates modular inverse of a number using Fermet's theorem
  *
  * @param  {Number} a Number for which inverse needs to be found
  * @param  {Number} m Mod val
  * @return {Number}   Modular Inverse
  */
-const modularInverse = (a, m) => {
-  const result = exEuclidean(a, m);
-  if (result.gcd !== 1) {
+const fermetModularInverse = (a, m) => {
+  if (a === 0 || m === 0) {
     return null;
   }
 
-  console.log(result);
-
-  return (result.x + m) % m;
+  return fastExp(a, m - 2, m);
 };
 
-module.exports = modularInverse;
-
 /**
- * Calculates modular inverse of a number using Fermet's theorem
+ * Calculates modular inverse of a number
  *
  * @param  {Number} a Number for which inverse needs to be found
  * @param  {Number} m Mod val
  * @return {Number}   Modular Inverse
  */
-const fermetModularInverse = (a, m) => fastExp(a, m - 2, m);
+const modularInverse = (a, m) => {
+  if (a === 0 || m === 0) {
+    return null;
+  }
+
+  const result = exEuclidean(a, m);
+
+  if (result.gcd !== 1) {
+    return null;
+  }
+
+  return (result.x + m) % m;
+};
 
-module.exports = fermetModularInverse;
+module.exports = {
+  fermetModularInverse,
+  modularInverse
+};