#177 Add neg method to negate a Big number.

MikeMcl · MikeMcl · commit 4418329d5c13 · 2022-06-04T14:24:18.000+01:00
diff --git a/big.js b/big.js
@@ -629,6 +629,16 @@
 
     return this.minus(x.times(y));
   };
+  
+  
+  /*
+   * Return a new Big whose value is the value of this Big negated.
+   */
+  P.neg = function () {
+    var x = new this.constructor(this);
+    x.s = -x.s;
+    return x;
+  };
 
 
   /*
diff --git a/big.mjs b/big.mjs
@@ -628,6 +628,16 @@ P.mod = function (y) {
 };
 
 
+/*
+ * Return a new Big whose value is the value of this Big negated.
+ */
+P.neg = function () {
+  var x = new this.constructor(this);
+  x.s = -x.s;
+  return x;
+};
+
+
 /*
  * Return a new Big whose value is the value of this Big plus the value of Big y.
  */
diff --git a/docs/index.html b/docs/index.html
@@ -103,6 +103,7 @@
       <li><a href="#lte"    >lte</a></li>
       <li><a href="#minus"  >minus</a></li>
       <li><a href="#mod"    >mod</a></li>
+      <li><a href="#neg"    >neg</a></li>
       <li><a href="#plus"   >plus</a></li>
       <li><a href="#pow"    >pow</a></li>
       <li><a href="#prec"   >prec</a></li>
@@ -207,7 +208,7 @@ <h5 id="big">
 new Big('-735.0918e-430')            // '-7.350918e-428'
 Big(435.345)                         // '435.345'
 new Big()                            // 'Error: [big.js] Invalid value'
-Big()                                // No error, and a new Big constructor is returned
+Big2 = Big()                         // No error, and a new Big constructor is returned
     </pre>
 
 
@@ -580,6 +581,17 @@ <h5 id="mod">mod<code class='inset'>.mod(n) <i>&rArr; Big</i></code></h5>
 
 
 
+    <h5 id="neg">neg<code class='inset'>.neg() <i>&rArr; Big</i></code></h5>
+    <p>
+      Returns a Big number whose value is the value of this Big number negated.
+    </p>
+    <pre>
+x = new Big(0.3)
+x.neg()                    // '-0.3'
+x.neg().neg()              // '0.3'</pre>
+
+
+
     <h5 id="plus">
       plus<code class='inset'>.plus(n) <i>&rArr; Big</i></code>
     </h5>
diff --git a/test/browser/test.html b/test/browser/test.html
@@ -13,6 +13,7 @@
   <!-- <script src='../methods/div.js'></script>           -->
   <!-- <script src='../methods/minus.js'></script>         -->
   <!-- <script src='../methods/mod.js'></script>           -->
+  <!-- <script src='../methods/neg.js'></script>           -->
   <!-- <script src='../methods/plus.js'></script>          -->
   <!-- <script src='../methods/pow.js'></script>           -->
   <!-- <script src='../methods/prec.js'></script>          -->
diff --git a/test/runner.js b/test/runner.js
@@ -10,6 +10,7 @@ console.log( '\n Testing big.js\n' );
   'div',
   'minus',
   'mod',
+  'neg',
   'plus',
   'pow',
   'prec',

-Original file line number
+Diff line change
   'div',
   'minus',
   'mod',
 +  'neg',
   'plus',
   'pow',
   'prec',