2.9 Rotate a matrix by 90 degrees

Mathematica mat = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; mat = Reverse[Transpose[mat]]

{{3,6,9}, {2,5,8}, {1,4,7}}

 

Matlab A=[1 2 3; 4 5 6; 7 8 9] A=rot90(A)

3 6 9 2 5 8 1 4 7

 

Maple A:=Matrix([[1,2,3],[4,5,6],[7,8,9]]); A:=ArrayTools:-FlipDimension(A,2);	[[3,2,1], [6,5,4], [9,8,7]]
A:=A^%T;	[[3,6,9], [2,5,8], [1,4,7]]

 

Fortran

Using additional copy for the matrix

program f  implicit none 
  integer(4) ::i,j 
  integer(4), ALLOCATABLE ::A(:,:),B(:,:) 
 
  A = reshape ([1,2,3,   & 
                4,5,6,   & 
                7,8,9],  & 
               [3,3], & 
               order=[2,1] & 
              ) 
  B=A 
  i=0 
 
  do j=UBOUND(A, 2),LBOUND(A, 2),-1 
     i=i+1 
     B(i,:)=A(:,j) 
  end do 
 
  do i=LBOUND(B, 1),UBOUND(B, 1) 
       print *,B(i,:) 
  end do 
 
end program f
 

mp>gfortran -std=f2008 f.f90 
tmp>./a.out 
           3           6           9 
           2           5           8 
           1           4           7