w_a_x_...@yahoo.com wrote:
> On Dec 25, 5:24 am, Xah Lee <xah...@gmail.com> wrote:
>
> > The JavaScript example:
> >
> > // Javascript. By William James
> > function normalize( vec ) {
> > var div=Math.sqrt(vec.map(function(x) x*x).reduce(function(a,b)
> > a+b)) return vec.map(function(x) x/div)
> >
> > }
> >
> > is also not qualified. (it is syntax error in SpiderMonkey engine
> > JavaScript-C 1.7.0 2007-10-03)
>
> Since you are using the latest version of Mathematica, you should
> also use the latest version of SpiderMonkey.
>
> The function works outside of a web browser with jslibs, and it
> works in Firefox 3.0.1.
>
> <html>
> <body>
>
> <script type="application/javascript;version=1.8"/>
>
> // Tested with Firefox 3.0.1.
> // SpiderMonkey JavaScript 1.6 added map().
> // 1.8 added reduce() and function shorthand:
> // function(x) { return x * x }
> // can now be:
> // function(x) x * x
>
> // Javascript. By William James
> function normalize( vec ) {
> var div=Math.sqrt(vec.map(function(x) x*x).reduce(function(a,b) a+b))
> return vec.map(function(x) x/div)
> }
>
> window.alert( normalize( [2,3,4] ).toSource() )
>
> </script>
>
> </body>
> </html>
Reduce:
procedure normalize vec;
begin scalar div;
div := for each u in vec sum u^2;
return map(~x/div, vec)
end;
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