diff --git a/src/__tests__/distance_matrix/creation.test.js b/src/__tests__/distance_matrix/creation.test.js
index 1b59287..ee72a79 100644
--- a/src/__tests__/distance_matrix/creation.test.js
+++ b/src/__tests__/distance_matrix/creation.test.js
@@ -83,6 +83,10 @@ describe('DistanceMatrix creation', () => {
     );
   });
 
+  it('fromCompact empty', () => {
+    expect(DistanceMatrix.fromCompact([]).to2DArray()).toStrictEqual([]);
+  });
+
   it('zeros', () => {
     expect(DistanceMatrix.zeros(3).to2DArray()).toStrictEqual([
       [0, 0, 0],
diff --git a/src/__tests__/distance_matrix/export.test.js b/src/__tests__/distance_matrix/export.test.js
index fbdf1ff..4aced5f 100644
--- a/src/__tests__/distance_matrix/export.test.js
+++ b/src/__tests__/distance_matrix/export.test.js
@@ -13,6 +13,10 @@ describe('DistanceMatrix export', () => {
     expect(matrix.toCompact()).toStrictEqual([1, 2, 3, 2, 3, 3]);
   });
 
+  it('toCompact empty', () => {
+    expect(new DistanceMatrix(0).toCompact()).toStrictEqual([]);
+  });
+
   it('toSymmetricMatrix', () => {
     const matrix = new DistanceMatrix([
       [0, 1, 2, 3],
diff --git a/src/__tests__/matrix/utility.test.js b/src/__tests__/matrix/utility.test.js
index 7bf7b50..e8328fc 100644
--- a/src/__tests__/matrix/utility.test.js
+++ b/src/__tests__/matrix/utility.test.js
@@ -45,6 +45,11 @@ describe('utility methods', () => {
     matrix.set(0, 0, 10);
     let called = 0;
 
+    /**
+     * @this {Matrix}
+     * @param i
+     * @param j
+     */
     function cb(i, j) {
       called++;
       expect(this).toBeInstanceOf(Matrix);
diff --git a/src/distanceMatrix.js b/src/distanceMatrix.js
index 75c620b..babdd29 100644
--- a/src/distanceMatrix.js
+++ b/src/distanceMatrix.js
@@ -97,6 +97,12 @@ export class DistanceMatrix extends SymmetricMatrix {
    */
   static fromCompact(compact) {
     const compactSize = compact.length;
+
+    if (compactSize === 0) {
+      return new this(0);
+    }
+
+    // compactSize in Natural integer range ]0;∞]
     // compactSize = (sideSize * (sideSize - 1)) / 2
     // sideSize = (Sqrt(8 × compactSize + 1) + 1) / 2
     const diagonalSize = (Math.sqrt(8 * compactSize + 1) + 1) / 2;
diff --git a/src/inspect.js b/src/inspect.js
index 66927dd..79500a4 100644
--- a/src/inspect.js
+++ b/src/inspect.js
@@ -1,6 +1,10 @@
 const indent = ' '.repeat(2);
 const indentData = ' '.repeat(4);
 
+/**
+ * @this {Matrix}
+ * @returns {string}
+ */
 export function inspectMatrix() {
   return inspectMatrixWithOptions(this);
 }
diff --git a/src/mathOperations.js b/src/mathOperations.js
index 221886b..2b8c306 100644
--- a/src/mathOperations.js
+++ b/src/mathOperations.js
@@ -801,7 +801,7 @@ export function installMathOperations(AbstractMatrix, Matrix) {
   AbstractMatrix.prototype.powS = function powS(value) {
     for (let i = 0; i < this.rows; i++) {
       for (let j = 0; j < this.columns; j++) {
-        this.set(i, j, Math.pow(this.get(i, j), value));
+        this.set(i, j, this.get(i, j) ** value);
       }
     }
     return this;
@@ -815,7 +815,7 @@ export function installMathOperations(AbstractMatrix, Matrix) {
     }
     for (let i = 0; i < this.rows; i++) {
       for (let j = 0; j < this.columns; j++) {
-        this.set(i, j, Math.pow(this.get(i, j), matrix.get(i, j)));
+        this.set(i, j, this.get(i, j) ** matrix.get(i, j));
       }
     }
     return this;
diff --git a/src/stat.js b/src/stat.js
index dc9d705..dbe558d 100644
--- a/src/stat.js
+++ b/src/stat.js
@@ -157,7 +157,7 @@ export function getScaleByRow(matrix) {
   for (let i = 0; i < matrix.rows; i++) {
     let sum = 0;
     for (let j = 0; j < matrix.columns; j++) {
-      sum += Math.pow(matrix.get(i, j), 2) / (matrix.columns - 1);
+      sum += matrix.get(i, j) ** 2 / (matrix.columns - 1);
     }
     scale.push(Math.sqrt(sum));
   }
@@ -177,7 +177,7 @@ export function getScaleByColumn(matrix) {
   for (let j = 0; j < matrix.columns; j++) {
     let sum = 0;
     for (let i = 0; i < matrix.rows; i++) {
-      sum += Math.pow(matrix.get(i, j), 2) / (matrix.rows - 1);
+      sum += matrix.get(i, j) ** 2 / (matrix.rows - 1);
     }
     scale.push(Math.sqrt(sum));
   }
@@ -197,7 +197,7 @@ export function getScaleAll(matrix) {
   let sum = 0;
   for (let j = 0; j < matrix.columns; j++) {
     for (let i = 0; i < matrix.rows; i++) {
-      sum += Math.pow(matrix.get(i, j), 2) / divider;
+      sum += matrix.get(i, j) ** 2 / divider;
     }
   }
   return Math.sqrt(sum);