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javascript/examples/1_5_vectors.js

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+"use strict";
+
+chapter("Vector and matrix operations");
+
+section("Scalar operations");
+const addS = (a, b) => a + b;
+const subtractS = (a, b) => a - b;
+const multiplyS = (a, b) => a * b;
+example("addS(2, 3)");
+example("subtractS(2, 3)");
+example("multiplyS(2, 3)");
+
+section("Vector operations");
+function transpose(matrix) {
+    const result = [];
+    for (let i = 0; i < matrix[0].length; i++) {
+        const row = [];
+        for (let j = 0; j < matrix.length; j++) {
+            row.push(matrix[j][i]);
+        }
+        result.push(row);
+    }
+    return result;
+}
+
+const apply = f => args => f(...args);
+const zipWith = f => (...args) => apply(map(apply(f)))(transpose(args));
+const sumV = v => sum(...v);
+
+const addV = zipWith(addS);
+const subtractV = zipWith(subtractS);
+const multiplyV = zipWith(multiplyS);
+const scalar = compose(sumV, multiplyV);
+example("addV([1, 2, 3], [4, 5, 6])");
+example("subtractV([1, 2, 3], [4, 5, 6])");
+example("multiplyV([1, 2, 3], [4, 5, 6])");
+example("scalar([1, 2, 3], [4, 5, 6])");
+
+section("Matrix operations");
+function multiplyM(a, b) {
+    return apply(map(ar => apply(map(curry(scalar)(ar)))(transpose(b))))(a);
+}
+const addM = zipWith(addV);
+const subtractM = zipWith(subtractV);
+example("addM([[1, 2], [3, 4]], [[5, 6], [7, 8]])[0]");
+example("addM([[1, 2], [3, 4]], [[5, 6], [7, 8]])[1]");
+example("subtractM([[1, 2], [3, 4]], [[5, 6], [7, 8]])[0]");
+example("subtractM([[1, 2], [3, 4]], [[5, 6], [7, 8]])[1]");
+example("transpose([[1, 2], [3, 4]])[0]");
+example("transpose([[1, 2], [3, 4]])[1]");
+example("multiplyM([[1, 2], [3, 4]], [[5, 6], [7, 8]])[0]");
+example("multiplyM([[1, 2], [3, 4]], [[5, 6], [7, 8]])[1]");