INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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.

Jobs

Add or subtract polar degrees in Excel

Add or subtract polar degrees in Excel

(OP)
Can some one please show me how to add or subtract polar degrees in MS Excel (2003).
I have two polar values (anywhere from 0 to 360 degrees), A1=10 A2=359.5 A3=MOD(A1-A2,360)which returns the correct value of 10.5
But.. if A1=350 and A2=359.5 A3=MOD(A1-A2,360) returns 350.5 and not the correct value of 9.5 degrees. Can this be fixed with a pile of "IF" .. THEN" statements.. or there must be a better way

Thank you for your time, it is very much appreciated.
Ralph




RE: Add or subtract polar degrees in Excel

(OP)
Yes.. technically but I would like to display the smaller of the two correct answers.. ie a difference of 20 degrees.
My simple spreadsheet,
A1 350 degrees
A2 10 degrees
A3=MOD(A1-A2,360) which returns 340.. which is correct but I want it to show 20 degrees.

RE: Add or subtract polar degrees in Excel

+20 or -20?

RE: Add or subtract polar degrees in Excel

Something like:

=MIN(MOD(A1-A2,360), 360-MOD(A1-A2,360))

RE: Add or subtract polar degrees in Excel

(OP)
Perfect.. Thank you very much bigsmile

RE: Add or subtract polar degrees in Excel

So, what answer do you "want" for 351 -> 14? 9+14 = 23 degrees? (Both of their differences from 360) or do you want (351-14) = 337

RE: Add or subtract polar degrees in Excel

Or am I mis-understanding your 10 -> 350 example? Where you wanted "20"?

RE: Add or subtract polar degrees in Excel

(OP)
Thank you racookpe
The solution that MintJulep (Mechanical) gave me is doing exactly what I wanted.
=MIN(MOD(A1-A2,360), 360-MOD(A1-A2,360))

RE: Add or subtract polar degrees in Excel

Seems like op wants the smallest measure of the angle between two vectors A1 and A2 without keeping track of the "polarity" of the result (polarity might otherwise be expressed as negative/positive, CW/CCW, A1 leads A2 or A2 leads A1).

In most applications (balancing for example), it would be important to track the polarity (sign) that results from vector subtraction. But we don't know his application.

=====================================
(2B)+(2B)' ?

RE: Add or subtract polar degrees in Excel

Sorry - I introduced vector subtraction which was not particularly implied by original post.

Maybe I should have just said he wants to know the distance between two angles, expressed as an angle less than 180 degrees, without regard for the polarity.

=====================================
(2B)+(2B)' ?

RE: Add or subtract polar degrees in Excel

Quote (electricpete)

he wants to know ..
Rather, I'm guessing at a word description which was never given in original post but can be inferred from the answer that he liked.

=====================================
(2B)+(2B)' ?

RE: Add or subtract polar degrees in Excel

(OP)
Sorry for all the confusion. I was making a spreadsheet that would do all kinds of calculations pertaining to balancing. Calculate various tolerances, force generated by a known unbalance, combine weights to a single location, divide a given weight into two components. And some other trivia. The question that started this was.. if I have a force at say 10 degrees and another at 345 degrees, what is the difference? It could be 25 or 335 degrees. For my application I wanted the smaller (shorter) value of 25.

RE: Add or subtract polar degrees in Excel

=DEGREES(ASIN(SIN(RADIANS(A1-A2))))

Polarity is maintained. If you want the absolute value, just add that function to the string.

But forces have magnitude as well as direction, so vector subtraction as electricpete suggested may be appropriate.

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!


Resources


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