3-D plot in matlab

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A A
A A 2013-11-24
回答： Wara Qasim 2019-10-1
Hey..I'm trying to plot the following code but i keep getting this error: (??? Error using ==> surf at 78 Z must be a matrix, not a scalar or vector.)
%% Defining givens:
f= 300e6; %% Chosen frequency
c= 3e8; %% Free space
lambda= c./f; %% Wavelenght
l_2=lambda./2;
k= (2.*pi)./l_2; %% Wave number
Io=5; % Chosen maximum value of the current
eighta=377; % Intrinsic impedance (free space)
r=l_2/(2.*pi); % Distance
h= 0:1:100; %% Variable height from the ground
L=1.25*l_2; % Dipole length
theta= 2*pi; %% Computing the requirements:
%% Electric field:
A= (k.*L.*Io.*exp(-1i.*r.*k))./(4.*pi.*r);
B= 2.*(cos(cos(theta).*k.*h));
E_F= eighta.*1i.*(A).*sin(theta).*(B);
[x,y,z]=sph2cart(h,theta-pi/2,E_F); % Converting to cartesian coordinates
% Generating 3D plot
surf(x,y,z) % Generating 3D plot
colormap(JET);
title ('Electric Field in 3D plot')
legend ('Heigth','Theta','Electric Field')
rotate3D on
axis image
Help!!

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采纳的回答

Azzi Abdelmalek
Azzi Abdelmalek 2013-11-24
编辑：Azzi Abdelmalek 2013-11-24
You can't use surf. Use
plot3(abs(x),abs(y),abs(z)) % Generating 3D plot
  1 个评论
A A
A A 2013-11-25
hey Azzi, thanks for your fast reply but when I used the command you gave me..it only resulted in a plot of one straight line and not 3D :(..do you have anything else to help me with??

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更多回答（1 个）

Wara Qasim
Wara Qasim 2019-10-1
hello please help me with this code i m trying to plot 3d figure of electric field but when i use plot3 i get error "Data cannot have more than 2 dimensions" and when i use quiver3 i get error that Z and U must be of same size. although sizes of all the matrices is same please help
clear all;
clc;
k = 9*10^9;
% Enter the Relative permittivity
eps_r = 1;
charge_order = 10^-9; % milli, micro, nano etc..
const = k*charge_order/eps_r;
x = 0:2:6;
y = 0:1:6;
z = 0:3:6;
[X,Y,Z]=meshgrid(x,y,z)
Y1=size(Y)
X1=size(X)
Z1=size(Z)
% Enter the dimensions
Nx=7;
Ny=4;
Nz=3;
% Enter the number of charges.
n = 2;
% Electric fields Initialization
E_f = zeros(Nx,Ny,Nz);
Ex = E_f;
Ey = E_f;
Ez = E_f;
% Vectors initialization
ex = E_f;
ey = E_f;
ez= E_f;
r = E_f;
r_square = E_f;
% Array of charges
Q = [2,-2];
% Array of locations
Z = [5,-5];
Y = [0,0];
X=[0,0];
%-------------------------------------------------------------------------%
% COMPUTATION OF ELECTRIC FIELDS
%-------------------------------------------------------------------------%
% Repeat for all the 'n' charges
for l = 1:n
q = Q(l);
% Compute the unit vectors
for i=1:Nx
for j=1:Ny
for k=1:Nz
r_square(i,j,k) = (i-51-X(l))^2+(j-51-Y(l))^2+(k-51-Z(l))^2;
r(i,j,k) = sqrt(r_square(i,j,k));
ex(i,j,k) = ex(i,j,k)+(i-51-X(l))./r(i,j,k);
ey(i,j,k) = ey(i,j,k)+(j-51-Y(l))./r(i,j,k);
ez(i,j,k) = ez(i,j,k)+(j-51-Z(l))./r(i,j,k);
end
end
end
E_f = E_f + q.*const./r_square;
Ex = Ez + E_f.*ex.*const;
Ey = Ez + E_f.*ey.*const;
Ez = Ez + E_f.*ez.*const;
end
e1=size(Ex)
e2=size(Ey)
e3=size(Ez)
plot3(abs(Ex),abs(Ey),abs(Ez))
%quiver3(X,Y,Z,Ex,Ey,Ez,'r');
%axis square;

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