Data update

Task/Gauss-Jordan-matrix-inversion/JavaScript/gauss-jordan-matrix-inversion.js

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+// Vector and matrix types
+// In JavaScript, we'll use arrays directly
+
+function printMatrix(matrix, title) {
+  console.log(title);
+  for (const row of matrix) {
+    console.log(row.map(x => x.toString().padStart(10)).join(''));
+  }
+}
+
+function createIdentityMatrix(n) {
+  const result = Array(n).fill().map(() => Array(n).fill(0));
+  for (let i = 0; i < n; i++) {
+    result[i][i] = 1;
+  }
+  return result;
+}
+
+function inverse(matrix) {
+  const n = matrix.length;
+
+  // Check if it's a square matrix
+  for (const row of matrix) {
+    if (row.length !== n) {
+      throw new Error("Not a square matrix");
+    }
+  }
+
+  // Create identity matrix for the result
+  const b = createIdentityMatrix(n);
+
+  // Create a copy of the input matrix
+  const a = matrix.map(row => [...row]);
+
+  for (let k = 0; k < n; k++) {
+    let iMax = 0;
+    let max = -1;
+
+    for (let i = k; i < n; i++) {
+      const row = a[i];
+
+      // Compute scale factor s = max abs in row
+      let s = -1;
+      for (let j = k; j < n; j++) {
+        const x = Math.abs(row[j]);
+        if (x > s) {
+          s = x;
+        }
+      }
+
+      if (s === 0) {
+        throw new Error("Irregular matrix");
+      }
+
+      // Scale the abs used to pick the pivot
+      const abs = Math.abs(row[k]) / s;
+      if (abs > max) {
+        iMax = i;
+        max = abs;
+      }
+    }
+
+    // Swap rows if needed
+    if (k !== iMax) {
+      [a[k], a[iMax]] = [a[iMax], a[k]];
+      [b[k], b[iMax]] = [b[iMax], b[k]];
+    }
+
+    const akk = a[k][k];
+
+    for (let j = 0; j < n; j++) {
+      a[k][j] /= akk;
+      b[k][j] /= akk;
+    }
+
+    for (let i = 0; i < n; i++) {
+      if (i !== k) {
+        const aik = a[i][k];
+        for (let j = 0; j < n; j++) {
+          a[i][j] -= a[k][j] * aik;
+          b[i][j] -= b[k][j] * aik;
+        }
+      }
+    }
+  }
+
+  return b;
+}
+
+function main() {
+  const a = [[1, 2, 3], [4, 1, 6], [7, 8, 9]];
+  printMatrix(inverse(a), "Inverse of A is:\n");
+
+  const b = [[2, -1, 0], [-1, 2, -1], [0, -1, 2]];
+  printMatrix(inverse(b), "Inverse of B is:\n");
+}
+
+// Run the main function
+main();