Thank you very much for your help! I think I start to understand
it better.
On Wednesday, 23 October 2013 at 14:48:52 UTC, John Colvin wrote:
On Wednesday, 23 October 2013 at 14:00:46 UTC, Yura wrote:
Dear all,
Thank you for your replies!
Regarding Julia - it seems to be interesting, but - it is too
fresh, and from what I understood, it is not compiled. I think
D language would be more interesting for me and suitable for
my needs (scientific computing).
Yes, numpy/scipy is OK, but since I have now some time I would
like to learn one compiled language which is more close to the
hardware,
"I have done some linear algebra in D. If you are comfortable
calling C functions, you can easily call into existing
solutions,
because it is trivial to call into C from D."
This is very interesting since as you know lots of code is
written in c. GSL is a good example. The only problem is how
to use it. The thing is that i don't know c, but the question
is whether I really need to be skilled in c to be able to call
c functions. My gut feeling is that no, I don't need to be
skilled. I have installed gsl on my computer. But what I need
is a good example of a code/codes on how to call this library
from d programming language. E.g. I have tried to use gsl. I
have written a code in c (simple.c):
-------
#include <stdio.h>
#include <gsl/gsl_sf_bessel.h>
double fun(double x)
//main (void)
{
// x = 5.0;
double y = gsl_sf_bessel_J0 (x);
// printf ("J0(%g) = %.18e\n", x, y);
return y;
}
----------------
Also, I have written a di file (simple.di):
----------------
extern (C):
double fun(double);
----------------
And finally, d code (simple.d):
------------------
import std.stdio, std.string, std.array;
import std.conv;
import std.stdio;
import simple;
void main(){
writeln( fun(10.0) );
}
------------------------------------
Unfortunately, when I compile it it says:
dmd simple.d simple.o
simple.d(8): Error: undefined identifier fun
Could one provide a working clear example how to use gsl in D?
I have tried SciD and it apparently works, though I did not
test it so far. I think a tutorial on how to use D in
scientific programming would be very appreciated and could
attract more people to D.
PS Thank all of you for helping.
Don't call everything the same name. At the very least don't
have the di and d file with the same name.
Once you've done that, it will compile but the linker will
start to complain. You will need to link to the gsl and
gslcblas libraries, making your compilation command this:
dmd test.d simple.o -L-lgsl -L-lgslcblas
The simplest possible example of using gsl would be this:
simpleGSL.d
import std.stdio;
extern(C) double gsl_sf_bessel_J0(double);
void main()
{
writeln(gsl_sf__bessel_J0(10));
}
compile with dmd -L-lgsl -L-lgslcblas simpleGSL.d
If you were doing this seriously you would want to create a
load of d or di files containing the extern(C) declarations for
all the different gsl things you need. Also, you might want to
take a look at dstep: https://github.com/jacob-carlborg/dstep
which might be able to auto-generate them all for you.
