Arbitrary function with parameter

[darknails]

Hi, I would like to know how to define a arbitrary mathematical
function with one variable and a list of paramter, like, f(x). For
example, in GSL library this is done as
/* Definition of an arbitrary function with parameters */

struct gsl_function_struct
{
double (* function) (double x, void * params);
void * params;
};

typedef struct gsl_function_struct gsl_function ;

#define GSL_FN_EVAL(F,x) (*((F)->function))(x,(F)->params)

and the usage is here:
http://www.gnu.org/software/gsl/manu...ction-to-solve

I wonder how one does it in C++?

Thanks.

[joosteto]

da*******@gmail.com wrote:

Hi, I would like to know how to define a arbitrary mathematical

double (* function) (double x, void * params);
http://www.gnu.org/software/gsl/manu...ction-to-solve

I wonder how one does it in C++?

If you're using gnu stuff anyway, "man stdarg" should do the trick (has
an example).
googling should tell you how to use it on different systems too.

[mlimber]

da*******@gmail.com wrote:

Hi, I would like to know how to define a arbitrary mathematical
function with one variable and a list of paramter, like, f(x). For
example, in GSL library this is done as
/* Definition of an arbitrary function with parameters */

struct gsl_function_struct
{
double (* function) (double x, void * params);
void * params;
};

typedef struct gsl_function_struct gsl_function ;

#define GSL_FN_EVAL(F,x) (*((F)->function))(x,(F)->params)

and the usage is here:
http://www.gnu.org/software/gsl/manu...ction-to-solve

I wonder how one does it in C++?

In C++, one would use a functor. See this for a description:

http://www.sgi.com/tech/stl/functors.html

See especially the example involving struct less_mag.

Cheers! --M