PROGRAM arith0
!
! Author:  Br. David Carlson
!
! Date:  January 25, 2018
!
! This program does a division, then multiplies by the denominator to
! see if the numerator is the result or if that product is a little off.

IMPLICIT NONE

REAL::numerator, denominator, quotient, product, error, relative_error

numerator = 1.0
denominator = 3.0
quotient = numerator / denominator;
product = quotient * denominator;

WRITE (*, *) 'Dividing ', numerator, ' by ', denominator
WRITE (*, *) 'The quotient is: ', quotient
WRITE (*, *) 'The product of the quotient and denominator is ', product

IF (numerator == product) THEN
   WRITE (*, *) 'The numerator and product appear to be equal.'
ELSE
   WRITE (*, *) 'The numerator and product are NOT seen as equal.'
END IF

numerator = 2.0
denominator = 3.7
quotient = numerator / denominator;
product = quotient * denominator;

WRITE (*, *) 'Dividing ', numerator, ' by ', denominator
WRITE (*, *) 'The quotient is: ', quotient
WRITE (*, *) 'The product of the quotient and denominator is ', product

IF (numerator == product) THEN
   WRITE (*, *) 'The numerator and product appear to be equal.'
ELSE
   WRITE (*, *) 'The numerator and product are NOT seen as equal.'
END IF

error = product - numerator
relative_error = error / numerator

WRITE (*, *) 'The error is ', error
WRITE (*, *) 'The relative error is ', relative_error

IF (ABS(relative_error) < 2.0E-6) THEN
   WRITE (*, *) 'The numerator and product are approximately equal.'
ELSE
   WRITE (*, *) 'The numerator and product are NOT approximately equal.'
END IF

END PROGRAM