We present an algorithm to find the relevant regions to expand a given Feynman integral in a given limit of momenta and masses. It is based on the strategy of expansion by regions in the alpha-representation. The program uses a geometric approach to the alpha-representation and an open-source package QHull to find convex hulls.

Once QHull is installed, the program can be downloaded and loaded as << asy.m+ (you can also download some examples). The main function is ARegs[ks,ds,cs,hi], where ks is the list of loop momenta (e.g., "$\{k\}$"), ds is the list of denominators (e.g., "$\{k^2 + mm, (k+p)^2 + mm\}$"), cs is the list of constraints (e.g., "$\{p^2 -> MM\}$") and hi is the list of scalings of kinematic invariants with respect to the small parameter x+ (e.g., "$\{M -> x^0, m->x^1\}$").

The output is a list of vectors specifying the scales of the denominator factors. For the example above, the output would be $\{\{0,2\},\{0,0\},\{0,-2\}\}$, corresponding to the regions (a-c) above. The notation for e.g. the first entry reads: $D_1\sim x^{2+A}$, $D_2\sim x^{0+A}$ (in the momentum representation), or alternatively $x_1\sim x^{-2+A}$, $x_2\sim x^{A}$ (in the alpha-representation).