Exponential integral E1 (x)
double exp_integral( double x )
Returns the value of exponential integral E1 (x)
EX1
void exp_integral_ex1() { double dx[2]= {2.0,9.0}; for(int ii = 0; ii<2 ; ii++) printf("%lf: %lf\n",dx[ii],exp_integral(dx[ii])); }
origin.h