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Taking derivatives of functions in Origin C

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T O P I C R E V I E W
gpoon	Posted - 07/21/2009 : 2:31:06 PM Origin Ver. 8 and Service Release (Select Help-->About Origin): SR4 Operating System: XP I am trying to take numerical derivatives of functions (not a dataset of points) in Origin C. I noticed that the NAG library doesn't have a function for differentiation for C (but does for Fortran). The GNU Scientific Library (GSL) does have such a function, but I cannot get it to work because, apparently, Origin C doesn't support calling external functions that return a struct type variable. So this is what I was trying in my "ocgsl.h" file: /* 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 ; GSL_EXPORT int gsl_diff_central (const gsl_function f, double x, double result, double *abserr); Does Origin C (or NAG) have a differentiation function (for functions) that I just don't know about? Is there any way to overcome this limitation of calling functions that return struct type variables? Many thanks!
4 L A T E S T R E P L I E S (Newest First)
gpoon	Posted - 07/27/2009 : 02:16:46 AM It works! Thanks!
Iris_Bai	Posted - 07/22/2009 : 11:36:09 PM Hi Gregory, Please try the following way to define a function pointer outside strcut: typedef double (* FUNC)(double x, void * params); struct gsl_function_struct { FUNC function; void * params; }; Iris
gpoon	Posted - 07/22/2009 : 6:04:23 PM Hi Iris! Thanks for your reply. When I tried to compile "ocgsl.h" as follows (using the example on OriginWiki was a template): #pragma dll(libgsl, header) // this is OC special pragma, // header keyword is to indicate libgsl.dll is in same location as this file #define GSL_EXPORT // for OC, this is not needed, so make it empty // you can directly search and copy gsl function prototypes here struct gsl_function_struct { double (* function) (double x, void * params); <--- void * params; }; typedef struct gsl_function_struct gsl_function ; GSL_EXPORT int gsl_diff_central (const gsl_function f, double x, double result, double *abserr); The compiler returns "Error, syntax error in function declaration" at the line marked with the arrow. What is my mistake? Thanks, Gregory
Iris_Bai	Posted - 07/21/2009 : 11:39:55 PM Hi, Could you give more details about not work, for example compiling error? Origin C doesn't support external functions that return a struct type variable, but support struct type as output variable. In your code above, gsl_function is a struct and in gsl_diff_central function it is a output variable, not a return value. So should work in Origin C. Any way, you can reference to: http://wiki.originlab.com/~originla/internal/index.php?title=Tutorial:Fitting_with_Integral_Function_using_GSL_routine http://ocwiki.originlab.com/index.php?title=OriginC:Calling_GNU_Scientific_Library Iris

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