The CM software implements the construction of ring class fields of imaginary quadratic number fields and of elliptic curves with complex multiplication via floating point approximations. Additionally it provides an implementation of the fastECPP algorithm for proving primality of integers. It consists of libraries that can be called from within a C program and of executable command line applications. For the implemented algorithms, see A. Enge, The complexity of class polynomial computation via floating point approximations, Mathematics of Computation 78 (266), 2009, pp. 1089–1107.
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See also https://www.multiprecision.org/paridroid/index.html for PariDroid, a port of PARI/GP to Android