Solver unable to find solution

[awaughtal]

Hello,

I am new to Mathcad and am trying to solve a set of linear equations. (Context: given environment and pipe pressure conditions, need to find minimum wall thickness)

I have tried many arrangements and tutorials, but am still not able to reach a solution. It's gotten to the point where I am literally out of ideas (I also tried to use range variables and matricies)

I doubt it is the equations, since I am referencing them directly from an industry standard.

File and reference material attached.

Any help would be very (GREATLY) appreciated,

Amy

[RichardJ · Accepted solution]

The problem is that the two sides of your equation evaluate to very large numbers: about 10^17 Pa^3, but you have your convergence tolerance, CTOL, set to the default 10^-3. Set CTOL to 1000 and it works.

[awaughtal]

Thank you so much, I had been trying to change CTOL in the Worksheet Options menu and it obviously wasn't working.

Do you mind looking at the second method on the sheet? And maybe explaining why that one isn't working as well? I forsee more Mathcad solving in my future, so additional insight would be good.

[RichardJ]

It's s numeric solve block, and will therefore not do symbolic substitution of one expression into another. It looks at your first equation, determines that b is an undefined variable, and quits with an error.

[awaughtal]

Ok I see, that makes sense.

Thank you again, you have spared me so much grief! I will finally get a good nights rest.

I hope something awesome happens to you this week!

Amy