☕️Pfaffine

Pfaffine aims to be the caffeine that wakes your program up when you work with Geminal wavefunctions.

Pfaffine is an numerical package for fast calculation of Pfaffian. This branch has its background relinked against an extended version of BLIS.

Requirements

C++ Compiler

• Compiler supports C++ 11;
• Compiler recognizes #pragma once;

Library and Others

• My BLIS library fork with skr2k & skmm. This API-dependence is explicit;

Build and Linking

Simple makefile is provided. One can copy the example make.darwin to make.inc and modify accordingly. make install builds and installs an instantiated library together with several templated headers into {Repository root}/dest.

Including directly the .tcc files is another way and it's more extensive in some sense.

Usage

One can select between templated C++ and conventinoal C99 interfaces, which are stored pfaffine.hh and pfaffine.h correspondingly.

Interfaces are further categorized into 2 types: full interface that requires large memory allocation done outside function calls and simplified ones that allocates memory automatically for the user.

Full interface looks like this in C++/C99, correspondingly. Note that it can also be called from Fortran:

template <typename T>
T skpfa(char uplo, unsigned n,
        T *A, unsigned ldA, unsigned inv,
        T *Sp1, T *Sp2, T *Sp3, T *Sp4, T *Sp5, unsigned npanel);

void cal_?skpfa_(fpType *Pfa, char *uplo, unsigned *n, fpType *A, unsigned *ldA, unsigned *inv,
        fpType *Sp1, fpType *Sp2, fpType *Sp3, fpType *Sp4, fpType *Sp5, unsigned *npanel);

Here in C99 interface the fpType denotes floating point type corresponding to character ? in function names, i.e. double for dskpfa, double complex for zskpfa, etc.

Following full interface is the simplified one, defined as:

template <typename T>
T skpfa(char uplo, unsigned n, T *A, unsigned ldA, unsigned inv);

void ?skpfa(fpType *Pfa, char uplo, unsigned n, fpType *A, unsigned ldA, unsigned inv);

In all cases above, A will be replaced by its full inverse if inv=1, otherwise the upper-half of tri-diagonal form will be kept. Detailed explanation for parameters referred here is available in docstring in src/skpfa.tcc.

Licensing

Source code forms under this branch are provided under the Mozilla Public License. As long as one keep modifications of these specific files open, they are is allowed to use it for whatever they like at her or his own risk.