Re: [Help-gsl] gsl newbie: GSL_EFAULT in

[Steve Brosnan]

Illes,

I too am pretty much a newbie, but I have successfully used the new (upgraded 
in gsl-1.15) ode solver. You are probably correct that you have not allocated 
things properly. I really encourage you to read Section 26 of the 
documentation, but here is the kernel of what I found to be important. New for 
gsl-1.15 is a higher level interface using the 'driver', which has worked fine 
for me. What you need to do is:
(1)  Define and load the gsl_odeiv2_system structure.
(2)  Allocate the driver with one of four options. I used 
gsl_odeiv2_driver_alloc_y_new. One of the call parameters is the 
gsl_odeiv2_step_type* that you have already noted.
(3)  Call gsl_odeiv2_driver_apply in your integration loop
(4)  Free memory when you're done with gsl_odeiv2_driver_free

Hope that helps.  

Best regards,

Steve


> 
> From: "Farkas, Illes" <address@hidden>
> To: address@hidden
> Subject: [Help-gsl] gsl newbie: GSL_EFAULT in
> 
> Dear GSL List,
> 
> Thanks to all for making the gsl library available to the public. I'm a
> newbie to gsl. In my program gsl_odeiv2_evolve_apply returns GSL_EFAULT. I
> use the rk2imp integration method with this line in my code:
> 
> gsl_odeiv2_step_type * stepType = gsl_odeiv2_step_rk2imp;
> 
> I assume that with this setting gsl_odeiv2_evolve_apply simply invokes the
> function rk2imp (defined in the file "rk2imp.c"). Based on line 263 of
> rk2imp.c I think that the above mentioned GSL_EFAULT return value is caused
> by state->driver == NULL, where "state" is the first argument of
> rk2imp_apply.
> 
> Do you think this conclusion is correct?
> 
> Do I need to define (or allocate memory to) this driver somewhere?
> 
> Or is this memory allocation problem a common newbie error?
> 
> Many-many thanks
> Illes
> --