https://github.com/xrq-phys/pfaffine

☕️ Pfaffian caffeine for Geminal wavefunction brews.
https://github.com/xrq-phys/pfaffine

blis lapack skew-symmetric

Last synced: 2 months ago
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☕️ Pfaffian caffeine for Geminal wavefunction brews.

• Host: GitHub
• URL: https://github.com/xrq-phys/pfaffine
• Owner: xrq-phys
• License: mpl-2.0
• Created: 2020-04-09T18:43:30.000Z (almost 5 years ago)
• Default Branch: blis
• Last Pushed: 2021-09-12T08:11:48.000Z (over 3 years ago)
• Last Synced: 2023-05-22T14:49:36.220Z (over 1 year ago)
• Topics: blis, lapack, skew-symmetric
• Language: C++
• Homepage:
• Size: 550 KB
• Stars: 7
• Watchers: 2
• Forks: 1
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
☕️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](https://github.com/flame/blis).

### Requirements

#### C++ Compiler

- Compiler supports C++ 11;

- Compiler recognizes `#pragma once`;

#### Library and Others

- My [BLIS library fork](https://github.com/xrq-phys/blis) 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:

```cpp

template 

T skpfa(char uplo, unsigned n,

        T *A, unsigned ldA, unsigned inv,

        T *Sp1, T *Sp2, T *Sp3, T *Sp4, T *Sp5, unsigned npanel);

```

```c

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:

```cpp

template 

T skpfa(char uplo, unsigned n, T *A, unsigned ldA, unsigned inv);

```

```c

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](https://www.mozilla.org/en-US/MPL). 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*.