Merge pull request #422 from CSnap/tan_fix

Added new util function that sends tan function infinities correctly
scratchfoundation · Feb 1, 2017 · 073ffda · 073ffda
2 parents fff63e3 + 1ac89f5
commit 073ffda
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Showing 4 changed files with 39 additions and 6 deletions.
diff --git a/src/blocks/scratch3_operators.js b/src/blocks/scratch3_operators.js
@@ -1,4 +1,5 @@
 var Cast = require('../util/cast.js');
+var MathUtil = require('../util/math-util.js');
 
 var Scratch3OperatorsBlocks = function (runtime) {
     /**
@@ -126,9 +127,9 @@ Scratch3OperatorsBlocks.prototype.mathop = function (args) {
     case 'floor': return Math.floor(n);
     case 'ceiling': return Math.ceil(n);
     case 'sqrt': return Math.sqrt(n);
-    case 'sin': return Math.sin((Math.PI * n) / 180);
-    case 'cos': return Math.cos((Math.PI * n) / 180);
-    case 'tan': return Math.tan((Math.PI * n) / 180);
+    case 'sin': return parseFloat(Math.sin((Math.PI * n) / 180).toFixed(10));
+    case 'cos': return parseFloat(Math.cos((Math.PI * n) / 180).toFixed(10));
+    case 'tan': return MathUtil.tan(n);
     case 'asin': return (Math.asin(n) * 180) / Math.PI;
     case 'acos': return (Math.acos(n) * 180) / Math.PI;
     case 'atan': return (Math.atan(n) * 180) / Math.PI;

diff --git a/src/util/math-util.js b/src/util/math-util.js
@@ -45,4 +45,24 @@ MathUtil.wrapClamp = function (n, min, max) {
     return n - (Math.floor((n - min) / range) * range);
 };
 
+
+/**
+ * Convert a value from tan function in degrees.
+ * @param {!number} angle in degrees
+ * @return {!number} Correct tan value
+ */
+MathUtil.tan = function (angle) {
+    angle = angle % 360;
+    switch (angle) {
+    case -270:
+    case 90:
+        return Infinity;
+    case -90:
+    case 270:
+        return -Infinity;
+    default:
+        return parseFloat(Math.tan((Math.PI * angle) / 180).toFixed(10));
+    }
+};
+
 module.exports = MathUtil;
diff --git a/test/unit/blocks_operators.js b/test/unit/blocks_operators.js
@@ -160,9 +160,13 @@ test('mathop', function (t) {
     t.strictEqual(blocks.mathop({OPERATOR: 'floor', NUM: 1.5}), 1);
     t.strictEqual(blocks.mathop({OPERATOR: 'ceiling', NUM: 0.1}), 1);
     t.strictEqual(blocks.mathop({OPERATOR: 'sqrt', NUM: 1}), 1);
-    t.strictEqual(blocks.mathop({OPERATOR: 'sin', NUM: 1}), 0.01745240643728351);
-    t.strictEqual(blocks.mathop({OPERATOR: 'cos', NUM: 1}), 0.9998476951563913);
-    t.strictEqual(blocks.mathop({OPERATOR: 'tan', NUM: 1}), 0.017455064928217585);
+    t.strictEqual(blocks.mathop({OPERATOR: 'sin', NUM: 1}), 0.0174524064);
+    t.strictEqual(blocks.mathop({OPERATOR: 'sin', NUM: 90}), 1);
+    t.strictEqual(blocks.mathop({OPERATOR: 'cos', NUM: 1}), 0.9998476952);
+    t.strictEqual(blocks.mathop({OPERATOR: 'cos', NUM: 180}), -1);
+    t.strictEqual(blocks.mathop({OPERATOR: 'tan', NUM: 1}), 0.0174550649);
+    t.strictEqual(blocks.mathop({OPERATOR: 'tan', NUM: 90}), Infinity);
+    t.strictEqual(blocks.mathop({OPERATOR: 'tan', NUM: 180}), 0);
     t.strictEqual(blocks.mathop({OPERATOR: 'asin', NUM: 1}), 90);
     t.strictEqual(blocks.mathop({OPERATOR: 'acos', NUM: 1}), 0);
     t.strictEqual(blocks.mathop({OPERATOR: 'atan', NUM: 1}), 45);

diff --git a/test/unit/util_math.js b/test/unit/util_math.js
@@ -34,3 +34,11 @@ test('wrapClamp', function (t) {
     t.strictEqual(math.wrapClamp(100, 0, 10), 1);
     t.end();
 });
+
+test('tan', function (t) {
+    t.strictEqual(math.tan(90), Infinity);
+    t.strictEqual(math.tan(180), 0);
+    t.strictEqual(math.tan(-90), -Infinity);
+    t.strictEqual(math.tan(33), 0.6494075932);
+    t.end();
+});