How do I plot a 3D graph of function that I have taken as input from the user?

Question

Nittya Ananda 2023-2-19

回答： Walter Roberson 2023-2-19

I want to write a code, where when I enter a function will return me a 3D plot of that function. This is the code I've written.

clc;
close all; 
syms x y
f = input("f(x,y)"); 
x1=-5:1:5;
y1=x1';
[X1,Y1]=meshgrid(x1,y1);
Z1=subs(subs(f,x,X1),y,Y1);
surf(X1,Y1,z1);

But, every time I run it, it shows me an error.

f(x,y) - x*y (FunctionI passed as input)

Error using surf

Data dimensions must agree.

Error in project_prac4 (line 9)

surf(X1,Y1,z1);

Answer 1

Walter Roberson 2023-2-19

z1 = subs(f, {x, y}, {X1, Y1});

You can only get away with subs(subs()) with scalars or with vectors with different orientations. You need simultaneous substitution for arrays.