PyMultiNest -- Python interface for MultiNest -- Michele's fork
Note: not completely committed yet... do not use for the moment!
PyMultiNest provides programmatic access to MultiNest from Python. It does so by building a Python extension that contains a C wrapper (the "bridge") to MultiNest's Fortran. By contrast, my approach is write a C-compatible wrapper in Fortran (using the iso_c_binding interface, a Fortran 2003 feature supported by modern compilers), and include it among the MultiNest source files. PyMultiNest can then access MultiNest directly using ctypes.
The C interface
The single MultiNest procedure that is exposed to C (for MultiNest 3.2) is
void run(bool nest_IS,bool nest_mmodal,bool nest_ceff, \
int nest_nlive,double nest_tol,double nest_ef,int nest_ndims,int nest_totPar,int nest_nCdims,int maxClst, \
int nest_updInt,double nest_Ztol,char nest_root[],int seed,int nest_pWrap[], \
bool nest_fb,bool nest_resume,bool nest_outfile,bool initMPI,double nest_logZero,int nest_maxIter, \
double (*loglike)(double *,int,int,void *context), \
void (*dumper)(int,int,int,double *,double *,double *,double,double,double,void *context),void *context);
(compare with the Fortran call as documented in the MultiNest README) and the two callbacks are
double loglike(double *Cube,int n_dim,int nPar,void *context);
void dumper(int nSamples,int nlive,int nPar, \
double *physLive,double *posterior,double *paramConstr, \
double maxLogLike,double logZ,double logZerr,void *context);
Installation
The Fortran wrapper (cwrapper.f90) needs to be added to the MultiNest source directory. Then the MultiNest library libnest3.so needs to be rebuilt after changing the Makefile by editing the line that defines NSOBJECTS.
NSOBJECTS = utils.o utils1.o priors.o kmeans_clstr.o xmeans_clstr.o posterior.o nested.o cwrapper.o
PyMultiNest is installed as usual with setup.py. Currently pymultinest_demo_minimal.py seems to work. The dumper interface may need more work.