There are many situations in which the integral of a function must be evaluated numerically between given limits. For C codes, there is a range of numerical integration (sometimes called numerical quadrature) functions provided within the GNU Scientific Library (GSL) (Galassi et al., 2009). However, in situations where the integrand has an extremely large dynamic range these GSL functions can fail due to numerical instability. One way to get around numerical instability issues is to work with the natural logarithm of the function. The logarithm of the function cannot simply be integrated as this will not produce the logarithm of the integral of the original function. lintegrate provides a range of C integration functions, equivalent to func...