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Question

Mathcad 15 Getting Vectors From For Loops

Forum|Forum|4 years ago
November 3, 2021
5 replies
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So I have a hw problem that doesn't need to be solved this way but I have a feeling I will be using the Modified bishops method on a future project so I wanna take my time on this. Basically, I have two equations :

This is a function to find the Factor of Safety for a slope under certain conditions. In the actual psi equation, the F is The same FS in the upper eq. This requires an iterative process where you guess a F run it through psi and then the FS function. You then compare F to the resulting FS to see how close they are. You continue guessing F until F and FS converge to a similar number. The summations with the variable I represent the 7 different vertical slices that are being summed to form the whole slope. I want to write a program where I can input F as a sequence like 1,2 .. n. It then should pick the first F and run it through psi summing over the 7 slices. This should output one character into the psi resultant vector. Overall once it has run through all F, I want the resultant psi to be an nx1 vector with each psi value pertaining to each F. Then I want it to run the FS equation, similar to the psi I want this to sum over the seven slices for each psi input. At the end, I should have a resulting FS vector with one FS value for each F value input. Here is what I have so far:

I am an absolute beginner with coding so any help would be greatly appreciated!

T

terryhendicott

21-Topaz II

Hi,

Can you please include the sheet with the posting.

Cheers

Terry

V

VladimirN

24-Ruby III

Please attach your Mathcad worksheet to the message.

T

terryhendicott

21-Topaz II

Hi,

We need to know the values of "l", "c", "w", "u", phi, and alpha to help you.

Cheers

Terry

T

terryhendicott

21-Topaz II

Hi,

Set up a solve block that will iterate to a solution automatically.

1_211104-SolveBlock.zip

S

StuartBruff

23-Emerald V

@AS_10102578 wrote:

So I have a hw problem that doesn't need to be solved this way but I have a feeling I will be using the Modified bishops method on a future project so I wanna take my time on this. Basically, I have two equations :

T At the end, I should have a resulting FS vector with one FS value for each F value input. Here is what I have so far:

I don't have your version of Mathcad (I've only got Prime Express 7). However, I can make a few comments on the code you've shown.

You are expecting ψ_F to be a vector and use it as such in the 2nd expression for FS. However, ψ_F doesn't exist as far as FS is concerned. ψ_F is a local variable within the first FS expression and doesn't exist outside of it. So what you needed to have done was assign the result to variable ψ_F instead of FS - this ψ_F is a different object to the ψ_F defined within the first expression.

A second problem you've got is that the ψ_F in the 1st expression is *not* a vector. All the expression is doing is assigning the summation result to ψ_F., overwriting any previous values. Consequently, the first FS simply has the value of ψ_F for F = 6. You need a second iterator to assign the results to a new element in ψ_F (you could use F, but only if any future F you have in mind continues to pull its values from an integer range).

The third problem is that you need an iterator (range variable or for/while loop) in the second expression to select each value of ψ_F; otherwise, you're just dividing the (intended) vector ψ_F into the top summation expression.

Unfortunately, my version of Mathcad doesn't allow programming, but I can show a (crude) version of your code that uses functions.

2021 11 04 A.png

Often, but not always, you can use vectorize operator to carry out parallel operations without using an iterator. Occasionally, you can write an expression so that Mathcad automatically iterates over an expression.

2021 11 04 B.png