Mathematica 7 compares to other languages

MRAB google at mrabarnett.plus.com
Fri Dec 26 01:46:54 CET 2008


sln at netherlands.com wrote:
> On Thu, 25 Dec 2008 21:50:29 +0000, Jon Harrop <jon at ffconsultancy.com> wrote:
> 
>> Xah Lee wrote:
>>>>> On Dec 10, 2:47 pm, John W Kennedy <jwke... at attglobal.net> wrote:
>>>>>> C:
>>>>>> #include <stdlib.h>
>>>>>> #include <math.h>
>>>>>> void normal(int dim, float* x, float* a) {
>>>>>>     float sum = 0.0f;
>>>>>>     int i;
>>>>>>     float divisor;
>>>>>>     for (i = 0; i < dim; ++i) sum += x[i] * x[i];
>>>>>>     divisor = sqrt(sum);
>>>>>>     for (i = 0; i < dim; ++i) a[i] = x[i]/divisor;
>>>>>> }
>>> Due to the low level of C, this C example should perhaps then accept a
>>> sequence of numbers separated by space...
>> In other words, you want a REPL.
>>
>> Why don't we have another challenge that involves handling a non-trivial
>> input format, i.e. parsing?
> 
> Maybe you could speed it up.
> 
> sln
> 
> ----------------------------------
> void normal (int Dimension, double *X, double *A)
> {
>      double *xp, *ap, divisor, sum;
>      int i;
> 
>      for ( i=0, sum=0., xp=X; i<Dimension; i++, xp++)
>           sum += (*xp) ** 2;

C doesn't have a "**" operator.

>      divisor = sqrt ( sum );
>      for ( i=0, ap=A, xp=X; i<Dimension; i++, ap++, xp++)
>           *ap = *xp / divisor;
> 
>      // if Dimension is greater than
>      // sizeof double X[] or double A[] it will GPF.
>      // this is a really, really bad design.
> }




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