topic Re: Solve for "a" symbolically, MC11 in Mathcad

Solve for "a" symbolically, MC11

SFares — Wed, 26 Nov 2025 16:15:40 GMT

Hello All,

How do I solve for "a" symollically? "a" represents the maximum cantilever length. (0.125) is the maximum deflection in inches at the end of "a". I have attached MC11 sheet.

Regards,

Sam

Re: Solve for "a" symbolically, MC11

Werner_E — Wed, 26 Nov 2025 17:53:00 GMT

Prime is able to solve your fourth order equation but its not able to display the result because it feels that its too large to display.

But you can assign the result a function in the four input arguments.

Once these arguments have values assigned you can evaluate this function. You will get all four solutions. Prime can't know if the results are real or not or which are positive or negative without knowing specific values for w1,E,I and L.

But I wonder why you would bother with symbolic calculations at all. If at the end you are just looking for numeric results its better to use Prime's numeric facilities - like the "root" function:

Re: Solve for "a" symbolically, MC11

SFares — Wed, 26 Nov 2025 18:57:13 GMT

Thank you Werner for providing different options. How did you get a_solution function to evaluate?

Regards,
Sam

Re: Solve for "a" symbolically, MC11

Werner_E — Wed, 26 Nov 2025 19:30:37 GMT

@SFares wrote:

Thank you Werner for providing different options. How did you get a_solution function to evaluate?

First I tried with "simplify" but I cancelled the operation because it took too long. Without "simplify" it finished within a reasonable time.

Re: Solve for "a" symbolically, MC11

SFares — Mon, 01 Dec 2025 13:36:49 GMT

Hello Werner,

When I tried the following, I get the message bad solve. Am I doing something wrong?I have MC 11.0.1.

Regards,

Sam

Re: Solve for "a" symbolically, MC11

Werner_E — Tue, 02 Dec 2025 08:48:08 GMT

"Bad solve variable" usually means that the variable was already assigned a value.

You can clear the variable completely by using clear(a) or clear its just for symbolic use by typing clear.sym(a).

Generally the assignment of the symbolic "solve" to a function is better done in front before any variables are defied.