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## [Help-gsl] root finding

 From: ghadir mohammadkhani Subject: [Help-gsl] root finding Date: Sun, 1 Aug 2010 01:47:56 -0700 (PDT)

Hello,
I want to solve as such integral:
\Int_{-PI/2}^{PI/2}  \sum_{i} cos(t) (dF(x_i,t)/dy) dt, in which x_i  is
obtained by solving the equation p(x)=0 , i.e.,  roots of function p are the
same x_i and the variable x varies between 0 to 1.
To obtain roots, I use subroutine gsl_root_fdfsolver_steffenson,   but receive
the massage the below:
gsl: steffenson.c:110: ERROR:  function value is not finite.
I think this error is removed with varying the initial guess, but I don't know
how should substitute it by other initial guess inside several loops.