Array assignments
Simple assignment:
U(2:N-1) = 0.5 * (U(1:N-2) + U(3:N))
Right-hand-side expression must conform with left-hand-side variable.
Conditional assignment:
WHERE (A .LT. 0.0) A = -A
The condition must be a logical array that conforms with the left-hand-side of the assignment.