[Aces-support] Odd F90 Question

[Tim Whitcomb]

Hi ACES folks:

This isn't necessarily a question about the ACES cluster, but there are 
many more skilled with Fortran 90 than me on this list, so this is 
submitted for your consideration.

I have a snippet of code that is giving some interesting numeric 
(integer!) results:

--------------------
...
trim_size = size(trim_data)
write (*,*) "Size of trim_data is    :", size(trim_data)
write (*,*) "Four times that is (?)  :", 4 * size(trim_data)
write (*,*) "4x stored integer is    :", 4 * trim_size
...
--------------------

trim_data is a real*4 array declared as
trim_data(min_lat:max_lat,min_lon:max_lon),
where m??_l?? are declared as integer, parameter with values 0,13,180,220.

when I run this, I get the following result:
--------------------
  Size of trim_data is    :          574
  Four times that is (?)  :         2012
  4x stored integer is    :         2296
--------------------

So, storing size(trim_data) in a separate integer variable and 
multiplying gives a different answer than just doing the explicit 
multiplication.  An unbiased third electronic vote, my calculator, 
claims that 4 * 574 is indeed 2296.

No doubt that this is probably something simple that I am missing, but 
I've stared at this too long.  Any ideas? I hope I have included all 
relevant information - this is built using pgf90 on a54-1727-032.

Tim

-- 
Timothy R. Whitcomb
===========================================
Research Assistant
Program on Atmospheres, Oceans, and Climate
Massachusetts Institute of Technology
office: Room 54-1611
         77 Massachusetts Avenue
	Cambridge, MA 02139
email:  ude_tim at mit.edu
===========================================