×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Performing array operations based on logicals

Performing array operations based on logicals

Performing array operations based on logicals

(OP)
Hi,
I'm new to FORTRAN and only have real experience in MATLAB.

What I've got is two arrays. If the elements in one array are less than a parameter, I want to perform an operation on the corresponding elements of the other array. Otherwise, I want to perform a different operation.

Since MATLAB indices can be logical arrays, this is how I would do it in MATLAB in 5 simple lines:

a = [1 3 5 7 9];
b = [0 2 4 6 8];
c = zeros(5,1);
c(a>4) = 3*b;
c(a<=4) = 2*b

This would result in
c = [0 4 12 18 24]

How would I go about doing this operation in FORTRAN? I could use an if loop nested in a do loop, but wouldn't that be inefficient? If FORTRAN does not have this similar capability to MATLAB, what would be a good algorithm to use in this case?

Thanks!

RE: Performing array operations based on logicals

The following won't work on F77. You have to be on at least F90.

CODE

program main
integer, dimension(5):: a, b, c

! a = [1 3 5 7 9];
a = (/ 1, 3, 5, 7, 9 /)
! b = [0 2 4 6 8];
b = (/ 0, 2, 4, 6, 8 /)
! c = zeros(5,1);
c = 0

! c(a>4) = 3*b;
where (a > 4) 
   c = 3 * b
else where
! c(a<=4) = 2*b
   c = 2 * b
end where

print *, c
end 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close