Error codes

In addition to the standard error codes for invalid arguments the functions can return the following values,

GSL_EMAXITER

the maximum number of subdivisions was exceeded.

GSL_EROUND

cannot reach tolerance because of roundoff error, or roundoff error was detected in the extrapolation table.

GSL_ESING

a non-integrable singularity or other bad integrand behavior was found in the integration interval.

GSL_EDIVERGE

the integral is divergent, or too slowly convergent to be integrated numerically.