FORTRAN - Assigning an array value to variable

Question

Is there a way to get the value of an array to the shape of a variable? Even when I select a single value of an array, say A(1:1, 1:1), it still complains when I compile and want to assign this to a variable:

Error: Incompatible ranks 0 and 1 in assignment at (1)

The goal in the end is something like this:

H = MAXVAL(matrix) - epsilon
IF ( matrix(i:i, i:i) >= H ) THEN

... but I cannot make this comparison because H is a variable and matrix(i:i, i:i) a 1x1 array. Is the only possibility for this to work to make H and array, too?

Thank you for your help!

Alexander Vogt · Accepted Answer · 2014-02-25 09:25:53Z

4

Do not specify a range, use a single element:

A(1,1)=1

Your statement would then read:

H = MAXVAL(matrix) - epsilon
IF ( matrix(i, i) >= H ) THEN

Background:

Fortran allows you to work on sub-arrays like:

A(1:10,2:5)

which would be a 10x4 array. So A(1:1,1:1) is in fact an array (1x1) (as you noted). A(1,1), on the other hand, is a scalar and can be treated as such.

answered Feb 25, 2014 at 9:25

Alexander Vogt

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1 Comment

Mz_Chen Over a year ago

Thank you! That worked! Guess the last time I tried it this way around and got an error, I was actually comparing with another array.

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