如何在 Fortran 中初始化二维数组 [英] How to initialize two-dimensional arrays in Fortran

问题描述

在 C 中，如果我没记错的话，您可以使用花括号语法轻松地初始化数组:

In C you can easily initialize an array using the curly braces syntax, if I remember correctly:

int* a = new int[] { 1, 2, 3, 4 };

当您希望使用特定的测试值初始化矩阵以用于数学目的时，如何在 Fortran 中为二维数组执行相同的操作?(不必在单独的语句中对每个元素进行双重索引)

How can you do the same in Fortran for two-dimensional arrays when you wish to initialize a matrix with specific test values for mathematical purposes? (Without having to doubly index every element on separate statements)

数组由

real, dimension(3, 3) :: a

或

real, dimension(:), allocatable :: a

推荐答案

你可以使用 reshape 和 shape 内在函数.类似的东西:

You can do that using reshape and shape intrinsics. Something like:

INTEGER, DIMENSION(3, 3) :: array
array = reshape((/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), shape(array))

但请记住列优先顺序.数组将是

But remember the column-major order. The array will be

1   4   7
2   5   8
3   6   9

整形后.

所以得到:

1   2   3
4   5   6
7   8   9

您还需要转置内在:

array = transpose(reshape((/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), shape(array)))

对于更一般的示例(具有不同维度的可分配二维数组)，需要 size 内在:

For more general example (allocatable 2D array with different dimensions), one needs size intrinsic:

PROGRAM main

  IMPLICIT NONE

  INTEGER, DIMENSION(:, :), ALLOCATABLE :: array

  ALLOCATE (array(2, 3))

  array = transpose(reshape((/ 1, 2, 3, 4, 5, 6 /),                            &
    (/ size(array, 2), size(array, 1) /)))

  DEALLOCATE (array)

END PROGRAM main

这篇关于如何在 Fortran 中初始化二维数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！