[Help-gsl] gsl optimization precision

[Jingchen Feng]

Hi,
I am using gsl to do optimization. The problem is I want the precision to be 
high. When I set the stop criteria to be:
status= gsl_multimin_test_gradient(s->gradient,1e-8);

I always get an error code, which tells the value of function can't be improved 
any more. After debugging for a whole day, I think the problem is the type of 
function return value is 'double', which limits the precision. However, It 
seems that gsl does not allow a long double return function to be optimized. Is 
there any way to solve this problem?

Thanks!