Help! "This variable is undefined"

[dpons]

I'm trying to use Mathcad to solve a series of equations. I keep getting the error message "This variable is undefined" Any tips?

[Werner_E · Accepted solution]

1) You forgot to type multiplication dots when calculating A.t * (....). If you write A.t(...) then A.t is interpreted as function.

2) You have a unit mismatch in your second equation. The first summand has to be multiplied by a length (I had simply multiplied by 1m which sure is not correct)

[dpons]

Thank you! Very helpful.

[Fred_Kohlhepp]

It intrigued me that your first solve block worked but the second one didn't.  I found two things from Werner's unit balance:

• , and
• You need to define A_t and A_s the same: 

These, along with Werner's fixes . . .

[ValeryOchkov]

Welcome to

Mathcad Mad House - Маткадовский дурдом

In this  Ward No. 17. Function or variable