In this guide, we will discuss Fortran Reshape Functions. The following table describes the reshape function:
| Function | Description |
|---|---|
| reshape(source, shape, pad, order) | It constructs an array with a specified shape shape starting from the elements in a given array source. If pad is not included then the size of source has to be at least product (shape). If pad is included, it has to have the same type as source. If order is included, it has to be an integer array with the same shape as shape and the values must be a permutation of (1,2,3,…,n), where n is the number of elements in shape , it has to be less than, or equal to 7. |
Example
The following example demonstrates the concept:
program arrayReshape
implicit none
interface
subroutine write_matrix(a)
real, dimension(:,:) :: a
end subroutine write_matrix
end interface
real, dimension (1:9) :: b = (/ 21, 22, 23, 24, 25, 26, 27, 28, 29 /)
real, dimension (1:3, 1:3) :: c, d, e
real, dimension (1:4, 1:4) :: f, g, h
integer, dimension (1:2) :: order1 = (/ 1, 2 /)
integer, dimension (1:2) :: order2 = (/ 2, 1 /)
real, dimension (1:16) :: pad1 = (/ -1, -2, -3, -4, -5, -6, -7, -8, &
& -9, -10, -11, -12, -13, -14, -15, -16 /)
c = reshape( b, (/ 3, 3 /) )
call write_matrix(c)
d = reshape( b, (/ 3, 3 /), order = order1)
call write_matrix(d)
e = reshape( b, (/ 3, 3 /), order = order2)
call write_matrix(e)
f = reshape( b, (/ 4, 4 /), pad = pad1)
call write_matrix(f)
g = reshape( b, (/ 4, 4 /), pad = pad1, order = order1)
call write_matrix(g)
h = reshape( b, (/ 4, 4 /), pad = pad1, order = order2)
call write_matrix(h)
end program arrayReshape
subroutine write_matrix(a)
real, dimension(:,:) :: a
write(*,*)
do i = lbound(a,1), ubound(a,1)
write(*,*) (a(i,j), j = lbound(a,2), ubound(a,2))
end do
end subroutine write_matrix
When the above code is compiled and executed, it produces the following result:
21.0000000 24.0000000 27.0000000 22.0000000 25.0000000 28.0000000 23.0000000 26.0000000 29.0000000 21.0000000 24.0000000 27.0000000 22.0000000 25.0000000 28.0000000 23.0000000 26.0000000 29.0000000 21.0000000 22.0000000 23.0000000 24.0000000 25.0000000 26.0000000 27.0000000 28.0000000 29.0000000 21.0000000 25.0000000 29.0000000 -4.00000000 22.0000000 26.0000000 -1.00000000 -5.00000000 23.0000000 27.0000000 -2.00000000 -6.00000000 24.0000000 28.0000000 -3.00000000 -7.00000000 21.0000000 25.0000000 29.0000000 -4.00000000 22.0000000 26.0000000 -1.00000000 -5.00000000 23.0000000 27.0000000 -2.00000000 -6.00000000 24.0000000 28.0000000 -3.00000000 -7.00000000 21.0000000 22.0000000 23.0000000 24.0000000 25.0000000 26.0000000 27.0000000 28.0000000 29.0000000 -1.00000000 -2.00000000 -3.00000000 -4.00000000 -5.00000000 -6.00000000 -7.00000000
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