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cdoherty1-Visitor
1-Visitor
Jul 19, 2013 10:40 AM UTC
Solved

Mathcad Help - Lookup and two way linear interpolation

Hi all,

I am a new user to Mathcad and I have came up against a very tough problem.

In the attachment (and image below) there is a table that looks up a value of Cy for a given K and M simple. The problem comes when the values for K and M are not a whole numbers for example - K=32 and M=0.23 then the value for Cy is in the range of 1.63 - 2.3. You need to interpolate between the four figures.

Cy will actually equal - 1.7348

I am looking to produce a Mathcad function that would allow me to look up any value of K and M.

DNV-RP-F109.JPG

You help is much appreciated.

Kind Regards

Chris.

Werner_E
Werner_EAnswer
25-Diamond I
Jul 19, 2013 12:54 PM UTC

This should help:

DNV_lookup.png

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10 replies

Werner_E
Werner_E25-Diamond I
25-Diamond I
Jul 19, 2013 11:49 AM UTC

This problem often comes up here in the forum and as often was solevd.

The >=140 would need some special treatment but thats not difficult, setting K to 140 for every value gretaer before the interpolation.

You wrote that you are after linear interpolation in the subsject, but you don't specify which version of Mathcad you use. Maybe you attach your Mathcad sheet to show what you have tried so far.

A thread of the near past which might be of interest to you:

http://communities.ptc.com/message/208694#208694 (see the function f_look() in the MC file)

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cdoherty1-VisitorAuthor
1-Visitor
Jul 19, 2013 12:25 PM UTC

Hi Werner Exinger,

Thank you so much for your reply. I am using Mathcad 15 and haven't really got anything to show yet.

I will have a look through the thread you suggested to see if I can come up with something before I send it to you.

Thanks again.

Chris.

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Werner_E
Werner_E25-Diamond IAnswer
25-Diamond I
Jul 19, 2013 12:54 PM UTC

This should help:

DNV_lookup.png

Translate
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