Mathcad 'forms of these values must match' error with unit assignment

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
Sign up Log in
1 reply · 14K views · last reply
markus.sparti
Messages
2
Reaction score
0
Mathcad help: "The forms of these values must match" error

Homework Statement


I am getting an error, when I assign a value to 'num', stating:

The forms of these values must match
This value has the form: Unitless,
but others have the form: f(any1, [unitless]) => [unitless]

I cannot figure out what the program wants me to do, how do I make the value of 'num := 100' match the others, or vise-versa? I am completely stuck. :rolleyes:


Homework Equations


Mathcad worksheet showing a shooting method setup: u70 := 0 as bootstrap condition, initial estimates u40, u50, u60 := 1, and three boundary conditions u1, u2, u3 evaluated at num+1 equal to 0.

Mathcad worksheet with constants ORIGIN, bar, P, delta, T and num, a gas constant R, diffusion coefficients D12 to D34, preliminary calculations of F12 to F34, dimensionless ratios r1 to r5, and dimensionless variables u1 to u4.

Mathcad worksheet with the heading Fourth order Runge-Kutta, showing a matrix of first derivatives D(eta, u) built from u1 to u7 and r1 to r5, followed by a call to rkfixed with a starting vector and num, and definitions of u1, u2 and u3.


with the error message:
Mathcad screenshot of the assignment S1(u40,u50,u60,u70) := rkfixed with a column vector of values 0.1183, 0.0788, 0.6858, u40, u50, u60, u70, followed by 0, 1.0, num, D, and a yellow error tooltip reading: The forms of these values must match.



The Attempt at a Solution


I have tried everything I can think of, I have double checked all the numbers and units and can't find anything wrong. Any help in the right direction is greatly appreciated.

Thanks! :approve:
 
Physics news on Phys.org

Discussion

IDK, it seems like it should work. MathCAD can be frustrating that way. Here's an example file from the help section. Try running that and then slowly morph it into your example. You'll need to change the file extension from .txt to .xmcd.