is D so slow?

[janderson]

baleog wrote:
> Hello
> I wrote 2 almost identical test programs(matrix multiplication). One on C and another on D. And D prorgram was 15 times slower! 
> Was it my mistake or not?
> Thank you
> 
> p.s. code:
> void test (int n) {  
>   float[] xs = new float[n*n];
>   float[] ys = new float[n*n];
>   for(int i = n-1; i>=0; --i) {
>     xs[i] = 1.0;
>   }
>  for(int i = n-1; i>=0; --i) {
>     ys[i] = 2.0;
>   }
>   float[] zs = new float[n*n];
>   for (int i=0; i<n; ++i) {
>     for (int j=0; j<n; ++j) {
>       float s = 0.0;
>       for (int k=0; k<n; ++k) {
>         s = s + (xs[k + (i*n)] * ys[j + (k*n)]);
>       }
>       zs[j+ (i*n)] =  s;
>     }
>   }
>   delete xs;
>   delete ys;
>   delete zs;
> }
> 


To me your code looks reasonable, although you probably want to take the 
startup time and the gc out of the equation since that cost is fixed. 
BTW: here's a slightly more optimal reverse loop:

for(int i = n; --i>0; )

-Joel