Index exceeds the number of array elements

Hi,

I've come across this program to show the 3d radiation plot for a dipole but I've come across an error

-Code-

clear all
clc
format short g
syms z theta lambda R
prompt = 'Enter the frequency=? '; 
freq = input(prompt);
prompt = 'Enter the antenna size=? '; 
length = input(prompt);
L = round(length*freq/3e8,3)*lambda; %Length of antenna in terms of lambda
k0 = 2*pi/lambda; %Phase constant
z0 = 120*pi; %Intrinsic impedance

I = sin(k0*(L/2-abs(z))); %Current distribution

E(theta,lambda,R) = (1i*z0*k0*sin(theta)*exp(-1i*k0*R)/(4*pi*R))*int(I*2*cos(k0*z*cos(theta)),z,0,L/2); %E-field at farzone
A=(1i*z0*k0*exp(-1i*k0*R)/(4*pi*R));
p=(sin(theta)*int(I*2*cos(k0*z*cos(theta)),z,0,L/2)); %The theta part of the E-field with the constant term
%Elimination the constant term from 'p'--%
Q=(int(diff(p),theta));
F = factor(Q,theta);
field_pattern(theta) = simplify(p/F(1));
%----------------------------------------%

new(theta)=simplify(Q/F(1));
 new2 = matlabFunction(new);
 
%------------------------------------------3D-pattern plot--------------------% 
v=0.1:pi/499:1*pi;
t=0:pi/499:2*pi;
t2=0:pi/499:pi;

[T,U] = meshgrid(t,v);
[T2,U2]=meshgrid(t2,v);
X = abs(new2(U)).*sin(U).*cos(T); 
Y = abs(new2(U)).*sin(U).*sin(T); 
Z = abs(new2(U)).*cos(U);


X2 = abs(new2(U2)).*sin(U2).*cos(T2); 
Y2 = abs(new2(U2)).*sin(U2).*sin(T2); 
Z2 = abs(new2(U2)).*cos(U2);


figure (1);
surf(X,Y,Z,abs(new2(U)));
shading interp
axis vis3d
axis equal
lighting gouraud
set(gca,'xtick',[])
set(gca,'xticklabel',[])
set(gca,'ytick',[])
set(gca,'yticklabel',[])
set(gca,'ztick',[])
set(gca,'zticklabel',[])
figure (2);
surf(X2,Y2,Z2,abs(new2(U2)));
shading interp
axis vis3d
axis equal
lighting gouraud
set(gca,'xtick',[])
set(gca,'xticklabel',[])
set(gca,'ytick',[])
set(gca,'yticklabel',[])
set(gca,'ztick',[])
set(gca,'zticklabel',[])
%---------------------------------E-field radiation pattern plot--------------%     
 
figure (3);
theta3=0:0.01:2*pi;
 
polar(theta3,abs(field_pattern(theta3))); %E-field radiation pattern
title(['Antenna length: ' num2str(round(length*freq/3e8,3))]);
view([90 -90]);
%-----------------------------------------------------------------------------%      

-Error-

Index exceeds the number of array elements (2).

Error in sym/factor (line 107)

multiplicity = double(c{k+1});

Error in dipole_pattern (line 20)

F = factor(Q,theta);

What do i adjust/change to remove the error?

Answer 1

[Torsten]

Q=(int(diff(p),theta));

should be p, shouldn't it ?

[Bertrand Ang]

Hi, could you elaborate further?

[Torsten]

Ok, I now see from your comment that you want the function without "constant term".

But your p is not a polynomial. So what is the "constant term" ?

Maybe

pconst = subs(p,theta,0)

and define p afterwards as

p = p - pconst

?

Q=(int(diff(p),theta));

at least is not reliable for this task.