Solving equations for Variable/Variable
1 view (last 30 days)
Show older comments
Isaac Kambouris
on 4 Sep 2021
Commented: Isaac Kambouris
on 6 Sep 2021
I have a simple question but i have not been able to find a way to achive this and was looking for some help. For example if I have the following code
syms A B C D E
eqn = (A*B*C)/E == D;
Is it there a function that will allow me to solve for C/D = ?. I have tried using solve but this provides a struct variable that solve the equation for c and D aka (solves for C= and D=).
Thanks
0 Comments
Accepted Answer
John D'Errico
on 5 Sep 2021
No reason you cannot do this:
syms A B C D E
eqn = (A*B*C)/E == D;
syms CoverD
solve(subs(eqn,C,CoverD*D),CoverD)
3 Comments
John D'Errico
on 5 Sep 2021
Just look. Take it apart.
syms A B C D E
eqn = (A*B*C)/E == D;
syms CoverD;
Effectively, I define the variable CoverD as C/D. So if we accept that
CoverD = C/D
then multiply by D. Can you solve for C? I hope so.
So what does this substitution do?
subs(eqn,C,CoverD*D)
It replaces C with the product CoverD*D. Now what happens to D in that expression? It effectively goes away, as long as D is not zero. And if D was zero, then what would be the meaning of the ratio C/D anyway? So we can assume D is never zero in this context.
The final solve should now be clear.
More Answers (0)
See Also
Categories
Find more on Assumptions in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!