Z must be a matrix, not a scalar or vector.

I could't find the Problem. Need a help!!!

%variable declare
syms x;
syms t;
%putting the value
a=1;
b=-2;
c=-1;
alpha=1;
p=0;
%mesh plot
x = -3:.1:3;
y = -3:.1:3;
[X,Y] = meshgrid(x,t);
%vartheta equation
vartheta = ((a/alpha)*X.^alpha)+((b/alpha)*p^alpha)+c*t;
%delta equation
delta=-(2*c)/(b*a^2);
%main function
Z=-(2*(c^2)*((tanh(sqrt(-delta).*vartheta)).^2))/(b*delta*a^3);
mesh(X,Y,Z)
grid on
hold on

Result:

Error using mesh (line 71)

Z must be a matrix, not a scalar or vector.

Error in M3_1_29_3 (line 30)

mesh(X,Y,Z)

[Torsten]

Why do you define

y = -3:.1:3

and don't use "y" anywhere in your code ?

And in order to plot, t must be given a value - i can't remain a symbolic variable.

Why do you use symbolic variables at all ?

[Jeffrey Clark]

Asuming you meant to use y or Y where t is used, vartheta should be computed as a matrix since X is used, and therefore Z would be a matrix. Since the error indicates that Z is not a matrix the code you shared must have other copy and paste issues. Please retest after removing the syms lines which may be causing some of the issue. Then upload that code if it still gives the error or something else.

Answer 1

[Walter Roberson]

%putting the value
a=1;
b=-2;
c=-1;
alpha=1;
p=0;
%mesh plot
x = -3:.1:3;
y = -3:.1:3;
[X,Y] = meshgrid(x,y);
%vartheta equation
vartheta = ((a/alpha)*X.^alpha)+((b/alpha)*p^alpha)+c*Y;
%delta equation
delta=-(2*c)/(b*a^2);
%main function
Z=-(2*(c^2)*((tanh(sqrt(-delta).*vartheta)).^2))/(b*delta*a^3);
mesh(X,Y,Z)
grid on
hold on