Hi,

I am working on a shaft torsion problem in SMath and I came accross 2 issues. The first one is related to the use of sum(4). I'm trying to sum l_1, l_2 and l_3. As you can see, sum(1) works fine but I wonder why sum(4) gives error (l_j is not defined):



I'm quite surprised that it doesn't work because I've found a similar example in "SMath Suite: A Primer" document:



Second issue is that I can't find out how to make a torque diagram. First I tried the way it's done in MathCAD (the example I'm working on here is from a book about MathCAD):



Then I tried with piecewise function and again something is wrong (the image below features also reference diagram from a book):



Of course M_s1, M_s2 and M_s3 are calculated first but I also tried with their values inside the if function and still didn't get any plot.

Here's the sm file: Torsion.sm (106kb) downloaded 8 time(s).

Thanks in advance for your help.

be careful to:
-subscript (which you get with the .) and vector index (which you get with [) are very different
- range is used to create a vector and not a range of values
- for diagrams the units of measurement must be managed

torsion_S.sm (105kb) downloaded 12 time(s).

sergio

Thank you very much for your help.



How can I type this part in equation system bracket (or is it a different type of curly bracket) ? It doesn't let me type if (or anything else) after M_s1.



I see that you fixed the first formulation used for the plot. But what changes were made to the second one (M(x)=|y=if ...) ? I can't see any difference and yet it generates a plot, unlike in my file (even after adding units under the plot like you did).



When it comes to l, this variable stands for length, that's why I don't use lambda.

This instruction is from the interactive handbook, accessible via extension manager.

... bar plot added

Torsion (Doctored plot).sm (121kb) downloaded 18 time(s).