README.md

Table of Contents

1. About The Project
2. Getting Started
   • Prerequisites
   • Installation
3. Usage
4. License
5. Contact

About The Project

tri_indices provides a mapping/inverse mapping from an index of an upper triangular matrix to an index of a one-dimensional array.

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Getting Started

Prerequisites

• gcc >= 9.4.0
• gfortran >= 9.4.0
• cmake >= 3.9

Installation

1. Clone the repo

   git clone https://github.com/yymmt742/tri_indices
   

2. Build fortran library

   mkdir build && cd build
   cmake ..
   make install
   

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Usage

   program main
     use mod_tri_indices
     implicit none
     integer :: i, j, k

     do j=1,10
       do i=1, j
         call pack_tri_indices(i, j, k) ! k = 1 ... 55
       end do
     end do

     do k=1,55
       call unpack_tri_indices(k=k, i, j) ! i and j are upper tri indeces
     end do

     do j=2,10
       do i=1, j - 1
         call pack_tri_indices(i, j, d=1, k) ! k = 1 ... 45
       end do
     end do

     do k=1,45
       call unpack_tri_indices(k=k, d=1, i, j) ! i and j are upper tri indeces without diagonal elements
     end do
   end program main

The following functions are available.

Subroutine	Arguments (intent(in))	Arguments (intent(out))	Description
pack_tri_indices(i,j,[d],k)	i, j, d(optional)	k	Maps the indices i,j of upper trianglar matrix to the index k of the packed 1-dimensional array.
unpack_tri_indices(k, [d], i, j)	k, d(optional)	i, j	Maps the index k of the packed 1-dimensional array to the indices i,j of upper trianglar matrix.

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License

Distributed under the MIT License. See LICENSE for more information.

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Contact

YYMMT742 - yymmt@kuchem.kyoto-u.ac.jp

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