How to change a Function by a Variable

11 次查看（过去 30 天）
ercan duzgun
ercan duzgun 2021-1-10
评论： ercan duzgun 2021-1-10
How can I change a MATLAB function with a variable? (They are symbolic equations.)
Assume that I have an equation of "A*sin(phi)+B*cos(phi)". I want to replace "sin(phi)" by "2*x/(1+x^2)" , and "cos(phi)" should by replaced by "2*x/(1+x^2)" ? (Notice that x=tan (phi/2) , therefore sin(phi)=2*x/(1+x^2), and cos(phi)=2*x/(1+x^2) ) .
The final symboic equation should look :
"A*2*x/(1+x^2) + B*2*x/(1+x^2)"
syms A B phi x
equation_current=A*sin(phi)+B*cos(phi)
% ??? Some unknown operations ???
equation_new=A*2*x/(1+x^2) + B*2*x/(1+x^2)

请先登录，再回答此问题。

采纳的回答

Mischa Kim
Mischa Kim 2021-1-10
编辑：Mischa Kim 2021-1-10
Ercan, here you go, for the first term:
syms phi x A B
eq = A*sin(phi) + B*cos(phi)
eq = subs(eq,sin(phi),2*x/(1+x^2))
  1 个评论
ercan duzgun
ercan duzgun 2021-1-10
Dear Mischa Kim,
Thank you very much. It works. I wasn't aware of this command. Thank you.

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Assumptions 的更多信息

标签

产品


版本

R2019b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by