js-hexfloat - npm Package Compare versions

Comparing version 0.2.0 to 0.3.0

hexfloat.js

@@ -22,17 +22,13 @@ /*
     };
-    var toHexString = function(canonical) {
+    var toHexString = function() {
         var sign = this < 0 ? '-' : '';
-        if (!canonical) {
-            return sign + '0x' + Math.abs(this).toString(16) + 'p0';
+        var a = Math.abs(this);
+        var p = 0;
+        if (a < 1) {
+            while (a < 1) { a *= 2; p-- }
         } else {
-            var a = Math.abs(this);
-            var p = 0;
-            if (a < 1) {
-                while (a < 1) { a *= 2; p-- }
-            } else {
-                while (a > 2) { a /= 2; p++ }
-            }
-            var es = p < 0 ? '' : '+';
-            return sign + '0x' + a.toString(16) + 'p' + es + p.toString(10);
+            while (a > 2) { a /= 2; p++ }
         }
+        var es = p < 0 ? '' : '+';
+        return sign + '0x' + a.toString(16) + 'p' + es + p.toString(10);
     };
@@ -39,0 +35,0 @@ // install

package.json

 {
   "name": "js-hexfloat",
-  "version": "0.2.0",
+  "version": "0.3.0",
   "description": "Rudimentary C99 Hexadecimal Float Support in JS",
@@ -5,0 +5,0 @@ "main": "hexfloat.js",

README.md

@@ -11,3 +11,3 @@ [![build status](https://secure.travis-ci.org/dankogai/js-hexfloat.png)](http://travis-ci.org/dankogai/js-hexfloat)
 var pi = parseHexFloat('0x1.921fb54442d18p+1'); // 3.14159265358982
-var piHex = Math.PI.toHexString();              // '0x3.243f6a8885a3p0'
+var piHex = Math.PI.toHexString();              // '0x1.921fb54442d18p+1'
 parseHexFloat(piHex) == Math.PI;                // true
@@ -36,23 +36,31 @@ ````
 
-### `Number.prototype.toHexString(canonical)`
+### `Number.prototype.toHexString()`
 
-Stringifies the number as a C99 hexadecimal notation.  Analogous to `"%a"` in C99 `sprintf()`. 
+Stringifies the number as a C99 hexadecimal notation like `"%a"` in C99 `sprintf()`. 
 
-#### CAVEAT
+#### Why Canonical Form?
 
-Unless `canonical` is `true`, the result is not canonical.  Canonically the first digit of the number is always `1` and the sign of the exponent is never omitted.
+From version 0.3.0, `.toHexString()` always returns the canonical notation.
 
-````C
-printf("%a\n", -57005.7458343505859375); // prints -0x1.bd5b7ddep+15
+````javascript
+Math.PI.toString(16);   // 3.243f6a8885a3 -> 0x3.243f6a8885a3p0 is valid yet uncanonical
+Math.PI.toHexString();  // 0x1.921fb54442d18p+1 is valid and canonical
 ````
 
-On the other hand, this implementation takes  advangage of the fact `Number.prototype.toString(16)` works for floating point numbers.  It just checks the number is negative and prepends '-' if so, then prepend '0x', and append 'p0'.
+It seems ok to just prepend '0x' and append 'p0' to `.toString(16)` to make a hex float.  Turns out it isn't.  It sometimes drops the last bit in some platforms.
 
-````javascript
-console.log((-57005.7458343505859375).toHexString());     // -0xdead.beefp0
-console.log((-57005.7458343505859375).toHexString(true)); // -0x1.bd5b7ddep+15
 ````
+Math.log(2).toString(16)  // 0.b17217f7d1cf78
+Math.log(2).toHexString() // 0x1.62e42fefa39efp-1
+````
 
-Even when not canonical, you can use the result interchangeably with C99 and other platforms that support the notation (C++11, Ruby, Perl 5.22 ...).
+````shell
+% perl -E 'say 0x0.b17217f7d1cf78p0 - 0x1.62e42fefa39efp-1'
+-1.11022302462516e-16
+% perl -E 'say sprintf "%a", 0x0.b17217f7d1cf78p0 - 0x1.62e42fefa39efp-1'
+-0x1p-53
+````
 
+And `abs(-0x1p-53)` is `DBL_EPSILON`.
+
 ## SEE ALSO
@@ -59,0 +67,0 @@

test/test.js

@@ -34,8 +34,6 @@ /*
        is(parseHexFloat('0xdead.beefp0'), dead_beef));
-    it('dead_beef == 0xdead.beefp0',
-       is((dead_beef).toHexString(), '0xdead.beefp0'));
-    it('('+dead_beef+').toHexString(true) == 0x1.bd5b7ddep+15',
-       is((dead_beef).toHexString(true), '0x1.bd5b7ddep+15'));
-    it('(1/'+dead_beef+')toHexString(true) == 0x1.264eb565bf921p-16',
-       is((1/dead_beef).toHexString(true), '0x1.264eb565bf921p-16'));
+    it('('+dead_beef+').toHexString() == 0x1.bd5b7ddep+15',
+       is((dead_beef).toHexString(), '0x1.bd5b7ddep+15'));
+    it('(1/'+dead_beef+')toHexString() == 0x1.264eb565bf921p-16',
+       is((1/dead_beef).toHexString(), '0x1.264eb565bf921p-16'));
     it('0xdead.beefp0 == 0x1.bd5b7ddep+15',
@@ -42,0 +40,0 @@ is(parseHexFloat('0xdead.beefp0'), parseHexFloat('0x1.bd5b7ddep+15')));

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Improved metrics

Number of lines in readme file

69

increased by13.11%

Worsened metrics

Total package byte prevSize

14041

decreased by-2.34%

Lines of code

91

decreased by-6.19%

No dependency changes