Fixed wrong result for l2Pool2d when sliding window having two valid elements

src/pool2d.js

@@ -1,8 +1,10 @@
 'use strict';
 
-import {Tensor} from './lib/tensor.js';
+import {Tensor, Scalar} from './lib/tensor.js';
 import {transpose} from './transpose.js';
-import {l2Reducer, meanReducer, maxReducer} from './reduce.js';
+import {pow} from './binary.js';
+import {sqrt} from './unary.js';
+import {maxReducer, meanReducer, sumReducer} from './reduce.js';
 import {validatePool2dParams} from './lib/validate-input.js';
 
 /**
@@ -120,5 +122,7 @@ export function maxPool2d(input, options = {}) {
  * @return {Tensor}
  */
 export function l2Pool2d(input, options = {}) {
-  return pool2d(input, l2Reducer, options);
+  const squaredInput = pow(input, new Scalar(2));
+  const pooledInput = pool2d(squaredInput, sumReducer, options);
+  return sqrt(pooledInput);
 }

src/reduce.js

@@ -101,6 +101,11 @@ export function meanReducer(previousValue, currentValue, currentIndex, array) {
   }
 }
 
+/* The sum reducer */
+export function sumReducer(previousValue, currentValue) {
+  return previousValue + currentValue;
+}
+
 /**
  * Compute the average value of all the input values along the axes.
  * @param {Tensor} input
@@ -140,8 +145,7 @@ export function reduceProduct(input, options = {}) {
  * @return {Tensor}
  */
 export function reduceSum(input, options = {}) {
-  return reduce(input,
-      (previousValue, currentValue) => previousValue + currentValue, options);
+  return reduce(input, sumReducer, options);
 }
 
 /**
@@ -164,17 +168,6 @@ export function reduceL1(input, options = {}) {
   return reduceSum(abs(input), options);
 }
 
-/* The l2 reducer */
-export function l2Reducer(previousValue, currentValue, currentIndex, array) {
-  if (currentIndex == 1) {
-    const sumOfSquares = previousValue * previousValue + currentValue * currentValue;
-    return sumOfSquares;
-  } else {
-    const sumOfSquares = previousValue + currentValue * currentValue;
-    return (currentIndex === array.length - 1) ? Math.sqrt(sumOfSquares) :sumOfSquares;
-  }
-}
-
 /**
  * Compute the L2 norm of all the input values along the axes.
  * @param {Tensor} input

test/l2pool2d_test.js

@@ -199,4 +199,22 @@ describe('test pool2d', function() {
     ];
     utils.checkValue(y, expected);
   });
+
+  it('l2Pool2d pads roundingType=ceil', function() {
+    const x = new Tensor([1, 1, 5, 5], [
+      1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11, 12, 13,
+      14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
+    ]);
+    const windowDimensions = [3, 3];
+    const padding = [1, 0, 0, 1];
+    const strides = [2, 2];
+    const y = l2Pool2d(x, {windowDimensions, padding, strides, roundingType: 'ceil'});
+    utils.checkShape(y, [1, 1, 3, 3]);
+    const expected = [
+      12.767145334803704, 17.175564037317667, 11.180339887498949,
+      38.1051177665153,   43.81780460041329,  26.92582403567252,
+      48.19751030914356,  53.056573579529235, 32.01562118716424,
+    ];
+    utils.checkValue(y, expected);
+  });
 });