fix(internals): compare both matrices' column counts in cosineSimilarityMatrix

typescript/src/internals/helpers/math.test.ts

@@ -0,0 +1,24 @@
+/**
+ * Copyright 2025 © BeeAI a Series of LF Projects, LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, expect, it } from "vitest";
+
+import { cosineSimilarityMatrix } from "@/internals/helpers/math.js";
+
+describe("cosineSimilarityMatrix", () => {
+  it("rejects matrices with differing column counts", () => {
+    expect(() => cosineSimilarityMatrix([[1, 2]], [[1, 2, 3]])).toThrowError(
+      "Matrices must have the same number of columns.",
+    );
+    expect(() => cosineSimilarityMatrix([[1, 2]], [])).toThrowError(
+      "Matrices must have the same number of columns.",
+    );
+  });
+
+  it("computes similarity for matching column counts", () => {
+    const result = cosineSimilarityMatrix([[1, 0]], [[1, 0]]);
+    expect(result[0][0]).toBeCloseTo(1);
+  });
+});

typescript/src/internals/helpers/math.ts

@@ -21,7 +21,7 @@ export function cosineSimilarity(vecA: number[], vecB: number[]): number {
 }
 
 export function cosineSimilarityMatrix(matrixA: number[][], matrixB: number[][]): number[][] {
-  if ((matrixA[0]?.length ?? 0) !== (matrixA[0]?.length ?? 0)) {
+  if ((matrixA[0]?.length ?? 0) !== (matrixB[0]?.length ?? 0)) {
     throw new ValueError("Matrices must have the same number of columns.");
   }