Completed constant

src/constant.js

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+'use strict';
+
+import {cast} from './cast.js';
+import {Tensor, sizeOfShape} from '../src/lib/tensor.js';
+/**
+ * Create a constant array of specified data type and shape,
+ * which contains data incrementing by step.
+ * @param {Number} start
+ * @param {Number} step
+ * @param {Array} outputShape
+ * @param {string} type
+ * @return {Tensor}
+ */
+export function constant(start, step, outputShape, type = 'float32') {
+  const outputElementCount = sizeOfShape(outputShape);
+  const data = [];
+  for (let i = 0; i < outputElementCount; i++) {
+    data.push(start + i * step);
+  }
+  const tensor = new Tensor(outputShape, data);
+  return cast(tensor, type);
+}

test/constant_test.js

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+'use strict';
+
+import {constant} from '../src/constant.js';
+import * as utils from './utils.js';
+
+
+describe('test constant', function() {
+  function testConstant(start, step, outputShape, type, expected) {
+    const outputTensor = constant(start, step, outputShape, type);
+    utils.checkShape(outputTensor, expected.shape);
+    utils.checkValue(outputTensor, expected.data);
+  }
+
+  it('constant step > 0', function() {
+    const expected ={
+      shape: [3, 3],
+      data: [
+        0, 1, 2,
+        3, 4, 5,
+        6, 7, 8,
+      ],
+    };
+    testConstant(
+        0, 1, [3, 3], 'float32', expected);
+  });
+
+  it('constant step < 0', function() {
+    const expected ={
+      shape: [3, 3],
+      data: [
+        9, 8, 7,
+        6, 5, 4,
+        3, 2, 1,
+      ],
+    };
+    testConstant(
+        9, -1, [3, 3], 'float32', expected);
+  });
+
+  it('constant step = 0', function() {
+    const expected ={
+      shape: [3, 3],
+      data: [
+        1, 1, 1,
+        1, 1, 1,
+        1, 1, 1,
+      ],
+    };
+    testConstant(
+        1, 0, [3, 3], 'float64', expected);
+  });
+
+  it('constant scalar', function() {
+    const expected ={
+      shape: [],
+      data: [42],
+    };
+    testConstant(42, 0, [], 'float64', expected);
+  });
+});