error in if-statement, requires scalar logical expression

Question

Within a subroutine I try to create a statement, however it will only work if I enter a number directly, as soon as I replace the number with a variable, it will give the er

Answer 1

From your comment var%type3 is a real, dimension(1,1). This isn't scalar, and var%type3 < 0.5 will be an array of the same shape.

As the error message states, the test condition for the if should be scalar logical. Depending on what you want to do your test condition can be one of a non-exhaustive list:

• var%type3(1,1) < 0.5
• ALL(var%type3 < 0.5)
• ANY(var%type3 < 0.5)

The first case seems natural as it is a scalar condition, but I leave the others as you may well be expanding to cases where it isn't a (1,1) array.

Answer 2

You try to use a DIMENSION(1, 1) type as a REAL.

You shoul add (1, 1) to access to yout REAL contained in the DIMENSION(1, 1)

Use :

  IF ( var%type3(1, 1) < 0.5 ) THEN
     print *, 'IT WORKS'
  END IF

Exemple to get this error :

MODULE vardef
  TYPE vartype
     REAL :: type3(1, 1)
  END TYPE vartype
END MODULE vardef

PROGRAM test
  USE vardef

  TYPE(vartype) var

  var%type3(1, 1) = 0

  IF ( var%type3 < 0.5 ) THEN
     print *, 'IT WORKS'
  END IF
  RETURN

END PROGRAM test