Borrar filtros
Borrar filtros

Problem adding two symbolic functions

7 visualizaciones (últimos 30 días)
Hossein
Hossein el 28 de Feb. de 2017
Comentada: Kuifeng Zhao el 18 de Mayo de 2021
Hi, I have a problem adding two fuctions with deriatives of symbolic variables. The main purpose ist to solve a differential equation for an amount of x and y to achieve Ux Uz. Can any body help me?
syms x y Ux Uz
U_x(x,y,Ux)=Ux*cos(x)*cos(y);
U_z(x,y,Uz)=Uz*cos(x)*cos(y);
A1=diff(U_x,x)+0.5*(diff(U_z,x))^2;
Error:
Error using symfun/privResolveArgs (line 181) Symbolic function inputs must match.
Error in sym/privBinaryOp (line 819) args = privResolveArgs(A, B);
Error in + (line 7) X = privBinaryOp(A, B, 'symobj::zip', '_plus');

Respuesta aceptada

Sid Jhaveri
Sid Jhaveri el 2 de Mzo. de 2017
Hi Hossein,
As the error suggests, both the inputs need to match. Try defining your U_x and U_z as follows:
U_x(x,y,Ux,Uz)=Ux*cos(x)*cos(y);
U_z(x,y,Ux,Uz)=Uz*cos(x)*cos(y);
After changing U_x and U_z as above, your code should work properly.
  1 comentario
Kuifeng Zhao
Kuifeng Zhao el 18 de Mayo de 2021
Thanks. I came across a similar problem with error "Error in *X = privBinaryOp(A, B, 'symobj::mtimes');" and your answer helped solved my problem.

Iniciar sesión para comentar.

Más respuestas (1)

Walter Roberson
Walter Roberson el 2 de Mzo. de 2017
A1 = diff(U_x(x,y,Ux),x)+0.5*(diff(U_z(x,y,Uz),x))^2;
That is, diff(U_x,x) gives a function result, as does diff(U_z,x), and then you were trying to add two functions with different arguments. But if you invoke U_x(x,y,Ux) then that becomes an expression result, and you diff() the two expressions and then you can add the expressions.

Community Treasure Hunt

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

Start Hunting!

Translated by