todo

数学公式库--非常不错 The GNU Scientific Library (GSL) is a collection of routines for numerical computing. T

* Reorganize siman interfaces to allow iterative use.

* Maybe the routines can be made to work with pointers instead of structs
  so that only pointer manipulation is done by the siman algorithm and
  there is no need for malloc. A call would look something like 
  siman(&start,&result, ...)