I have tried with inthp, intgrat, and ingquad. Compared with Matlab's quadgk, the results from Gauss were disappointing. I was wondering whether Aptech could develop something similar to (and as powerful as ) quadgk.
Aptech is considering a new version of inthp, or new function entirely that would handle singularities. Matlab's quadgk function also handles complex functions and "waypoints" which allow, for example, for contour integration. Would either of these latter features be important to you?
Yes, these mentioned features are important. Please note that there are existing FORTRAN and Octave codes (for quadgk and some extensions) that can be adapted to GAUSS codes.