Solve block and two, different length, data arrays

[YO_10021171]

I have the following problem. I have a vector containing 5 possible volt values and another vector containing 3 current values. I want to calculate in a solve block what the needed resistance is needed (according to ohm law). I can't figure out what is wrong with my solution.

Thanks 🙂

[terryhendicott]

No need for a solve block

[YO_10021171]

Thanks for the reply. This won't work when I don't have the exact equation for R. For example, what if I have (V+R+I)^4=3? I wanted to use a solve block for a more general solution.

[terryhendicott · Accepted solution]

Hi,

It is possible to generalize the solution by using the symbolic equation solver assigned to a function.  Then to use this function to assign the R matrix.

In the case of the equation quoted there are four answers so R is a nested matrix.

[Fred_Kohlhepp]

I am a firm believer in the proper use of units; it's one of the reasons Mathcad is such a useful tool for engineers (and others.)

• Your example { (V+R+I)^4 =3 } will choke Mathcad, the units won't balance.

             

• Do you have an example of a real world situation where Ohm's Law doesn't hold?

[LucMeekes]

Given that the example is bad in terms of units (See Fred's remark), you don't have a problem at hand with many equations and many unknowns. You only have a single equation with a single unknown. This can be solved with a solve block like this (This is Mathcad Pre version 15, it should look differently in Prime):

But you could also use the root function...

Now you can use the function Sol(V,I) to find each of your R-values:

Success!
Luc

[YO_10021171]

I didn't know you could define a function that way, thanks a lot this is exactly what I wanted