add thomas algorithm in javascript

contents/thomas_algorithm/code/javascript/thomas.js

@@ -0,0 +1,29 @@
+function thomas(a, b, c, x) {
+  const result = [];
+  const y = [];
+
+  y[0] = c[0] / b[0];
+  result[0] = x[0] / b[0];
+
+  for (let i = 1; i < a.length; i++) {
+    const scale = 1 / (b[i] - a[i] * y[i - 1]);
+    y[i] = c[i] * scale;
+    result[i] = (x[i] - a[i] * result[i - 1]) * scale;
+  }
+
+  for (let i = a.length - 2; i >= 0; i--)
+    result[i] -= y[i] * result[i + 1];
+
+  return result;
+}
+
+let a = [0, 2, 3];
+let b = [1, 3, 6];
+let c = [4, 5, 0];
+let x = [7, 5, 3];
+
+console.log("The system,");
+console.log("[1.0  4.0  0.0][x] = [7.0]");
+console.log("[2.0  3.0  5.0][y] = [5.0]");
+console.log("[0.0  3.0  6.0][z] = [3.0]");
+console.log("has the solution:\n", thomas(a, b, c, x));

contents/thomas_algorithm/thomas_algorithm.md

@@ -119,6 +119,8 @@ You will find this algorithm implemented [in this project](https://scratch.mit.e
 [import, lang:"nim"](code/nim/thomas_algorithm.nim)
 {% sample lang="cpp" %}
 [import, lang:"c_cpp"](code/c++/thomas.cpp)
+{% sample lang="js" %}
+[import, lang:"javascript"](code/javascript/thomas.js)
 {% endmethod %}
 
 <script>