Hi all, new SMath user here (transitioning from Mathcad). I am trying to recreate some of my old Mathcad sheets and have run into an issue for a scenario involving a for loop and multiple if statements. Hopefully this image works:



Any ideas as to what might be going on?

Thanks,
FT

Hello [userlink]gth802s[/userlink]

Definitions inside cases() arguments should be avoided.

Wrote

I have to point out once again that in general you shouldn't put definitions inside cases().
Unlike if(), when a condition or a case fails instead of throwing an error the whole function is returned like if doesn't exists. The consequence is that every argument is exposed and preprocessed, with potential unwanted behaviors respect to the expected logic. This is on the edge of SMath possibilities, but is what makes possible to use cases() whereas if() usually fails.

In your case it should look like in the screenshot below:




Notice that I initialize a local variable to avoid unintentional inheritance of existing vectors (if you call it twice and the second time h has less values than the first time, the second s.c_ctr will be the first vector with the initial values updated)

Thanks for the responses so far. I think my problem is that the Boolean is somehow incomplete. I ran the iterations manually and the for loop works fine until j=4, but then the conditions change at j=5 saying that the variable is not defined. But I am not quite sure what the missing condition is; I guess Mathcad is more tolerant of this?

Thanks again.

Hi. In the last expression before the otherwise, isn't a subscript j missing?



Best regards.
Alvaro.

I figured it out; it was a simple case of a missing subscript (as Alvaro pointed out) and parentheses in the wrong place... Should have stepped away from the computer sooner for that coffee; it was pretty clear what I had done wrong when I came back to my desk :-)

Thanks all; appreciate the quick responses!

It seems that your office lacks adequate modern equipment.



Best regards.
Alvaro.

Wrote

Thanks for the responses so far. I think my problem is that the Boolean is somehow incomplete.

.
Attach the Smath document for doctoring !

There is room for improvements in the conditions management.

Since the first case catches all the conditions where OCR[j] <= 1, the 2nd and third "(OCR[j] > 1) AND" checks are redundant.

Also, since Sigma'vf_ctr[j] <= pc[j] case is captured in the second condition, the third case can be written in the otherwise placeholder.

Good catch :-) Here is the conceptual model for the soil consolidation problem which is what this sheet is written to solve. When the final stress exceeds p_c, the soil undergoes additional settlement in the second region whose slope is denoted by C_c. The reason I coded it like that is it makes it easier for me to explain to students that it is an increment of stress (beyond the pressure denoted by p_c) that causes soil settlement in that region.



This is also the reason why I try to code things as explicitly as possible (including in the if statements) so that the students can follow along easier.

Really appreciate all the thoughtful responses from everyone; loving the SMath community already!

Wrote

Wrote

There is room for improvements in the conditions management.

If I didn't made a mistake, this is most simplified I could get.
Here is the file contains logarithmic simplification steps.

Regards

cases_simplified.sm (35 KiB) downloaded 27 time(s).

Wrote

... it makes it easier for me to explain to students ...

Wait, are you a teacher too?
How is everyone in this forum a teacher, academic, professor?
Am I the only simpleton here?

I am a practicing engineer with a PhD but I also teach a graduate level course at the local university (Georgia Institute of Technology). I am also living proof that having a PhD or being a professor doesn't make one any better/smarter than someone who is not an academic :d

Wrote

Wrote

... it makes it easier for me to explain to students ...

Wait, are you a teacher too?
How is everyone in this forum a teacher, academic, professor?
Am I the only simpleton here?

Wrote

Attach the Smath document for doctoring !

Give your data set of points
That will be enough to fit

Don't attach your smath document.
Issue is already solved, no need for demands.

Wrote

Give your data set of points
That will be enough to fit

Your log fit comes from Cat in the Hat.
A fitting session might be otherwise realistic,
while being more universal wrt to data collection.
As well more profitable for Students.