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Re-arranging formula

gbradley
1-Newbie

Re-arranging formula

Guys

This should be pretty straight forward for someone who knows Mathcad prime3 - As I'm pretty useless at rearranging formula's can mathcad prime 3 do this for me?

See attached

Thanks

8 REPLIES 8

I'm trying to make alpha the subject - I think I'm doing this right  but its coming up with solution not possible?  If I was to give the lambda1 etc figures would I get an answer?

This is Prime 3.1.

Those of us still in 3.0 would like to help, but . . .

RichardJ
19-Tanzanite
(To:gbradley)

As Fred says, we would like to help, but those of us with Prime 3.0 can't read your Prime 3.1 file. If you post a pdf of your worksheet you might get more suggestions.

I would do but it Looks like I can only upload a picture of 2mb?

Fred/Richard, just manage to add the PDF but I think its started a new thread.  I was thinking solve blocks but little unsure how to use them and whether it even works

I, too, was not able to read Prime 3.1 files and can now see what you are doing.

Did you notice that different alphas in your sheet look different.

Some are formatted as constant and refer to the predefined constant alpha = 0.007297...

Only the alpha in the exponent is labeled as "variable" (or better, its labeled "-", meaning autodetect).

If I retype your expression the same way you did, I get an answer from the symbolic processor. I don't see, why you didn't and you haven't included the error message (it may be meaningless, anyway) in the picture.

I guess, the result I got is not what you wanted, as of the different alphas.

If I change the constants alphas to variables, the symbolics can't find a solution. I would have been surprised if the symbolics could come up with a solution for that equation (EDIT: and now, that the symbolics actually found a solution, I am surprised ).

My next try was a solve block and given a guess value greater that 1 it find a solution. Hope this is what you are looking for.

As you can see I had to turn lambda11 and lambda22 into functions dependent on alpha.

Attached sheet is in Prime 3.0 format and you should be able to read it without problems with P3.1-

EDIT: I just realized that the last result is the very same which I got in the first place using the symbolics. Now I am a bit confused

You'll have to double check the answer.

EDIT2: That behavior of Prime is quite strange and inconsequential. While we see that alpha is interpreted as predefined constant in the first picture, when it comes to solving, the symbolics interprets alpha as the to solve for variable and we get the correct solution.

In the second picture, when we manually set the two alphas to label "variable" , the symbolics fails, for reasons unknown to me. But if we label all the other alphas (which are set to "-", meaning automatic labeling) manually at "variable", the symbolics again finds the solution. Strange!

Gareth,

I converted your Mathcad Prime worksheet in PDF and XPS file formats which can be found in attachment.

-MFra-
21-Topaz II
(To:gbradley)

for Gareth 1.jpg

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