C++ (Cpp) gsl_sf_log_1plusx_mx Examples

Example #1

File: cdfwchisq.c Project: ahnitz/lalsuite

//find bound on tail probability using mgf, cutoff point returned to *cx
REAL8 errbound(qfvars *vars, REAL8 u, REAL8* cx)
{

   REAL8 sum1, x, y, xconst;

   (vars->count)++;           //Increase counter

   xconst = u * vars->sigsq;  //xconst = u * sigma**2 + sum{ }
   sum1 = u * xconst;         //sum1 = u**2 * sigma**2 + sum{ } this is almost the equation after eq 9 in Davies 1973
                              //without the factor of 1/2 (applied at the end of this function)
   u *= 2.0;
   for (INT4 ii=vars->weights->length-1; ii>=0; ii--) {
      x = u * vars->weights->data[ii];       //x=2*u*lambda_j
      y = 1.0 - x;                           //y=1-2*u*lambda_j
      xconst += vars->weights->data[ii] * (vars->noncentrality->data[ii] / y + vars->dofs->data[ii]) / y;
      sum1 += vars->noncentrality->data[ii] * (x*x/(y*y)) + vars->dofs->data[ii] * (x*x / y + gsl_sf_log_1plusx_mx(-x));
   }
   *cx = xconst;

   return exp1(-0.5 * sum1);

}/* errbound() */

Example #2

File: Log.c Project: codahale/ruby-gsl

static VALUE Log_log_1px_mx(VALUE self, VALUE x) {
  return rb_float_new(gsl_sf_log_1plusx_mx(NUM2DBL(x)));
}