Why am I getting an answer "1×0 empty double row vector"?

In thi s script I was asked to solve a quadaric equation that would give me complex numers. With the complex numbers in an array i need to find when the roots of the real and imaginary parts are of equal magnitude. Then plot these roots using green triangles. The solution should consist of 2 complex conjugate pairs (you may ignore solutions at the origin).

I was told to use the find() command but seem to be struggling with it and getting answers to plot.

Here is my code.

clear; 
close all 
clc
alpha1 = 3; alpha2 = 1.2; alpha3 = 4; 
beta = -1:1e-3:2;

a = (1./beta);
b = (alpha1.*beta.^3) - alpha2;
c = alpha3.*beta;

s1 = (-b + sqrt(b.^2-(4.*a.*c)))./(2.*a);
s2 = (-b - sqrt(b.^2-(4.*a.*c)))./(2.*a);

s1real = real(s1);
s1imag = imag(s1);
s2real = real(s2);
s2imag = imag(s2);


plot(s1real, s1imag, 'b')
hold
plot(s2real, s2imag, 'b')
grid on 
axis([-4 2 -2 2]);
xlabel('Real(s)') 
ylabel('Imag(s)') 

line([0 0], ylim);  % draw x-axis 
line(xlim, [0 0]);  % draw y-axis 

[s1Imag_max,beta_max1]=max(s1imag);
beta_maxImag1 = beta(beta_max1)

[s2Imag_max,beta_max2]=max(s2imag);
beta_maxImag2 = beta(beta_max2);

s1real_red = s1real(beta_max1);
s1imag_red = s1imag(beta_max1);
plot(s1real_red,s1imag_red,'ro')
s2real_red = s2real(beta_max2);
s2imag_red = s2imag(beta_max2);
plot(s2real_red,s2imag_red,'ro')

s1real_abs = abs(s1real);
[s1Im_zeroReal, beta_zero1] = min(s1real_abs);
beta_zeroReal = beta(beta_zero1)

s2real_abs = abs(s2real);
[s2Im_zeroReal, beta_zero2] = min(s2real_abs);
beta_zeroReal2 = beta(beta_zero2);

s1real_black = s1real(beta_zero1);
s1imag_black = s1imag(beta_zero1);
plot(s1real_black,s1imag_black,'ks')
s2real_black = s2real(beta_zero2);
s2imag_black = s2imag(beta_zero2);
plot(s2real_black,s2imag_black,'ks')

s1imag_abs = abs(s1imag);
s2imag_abs = abs(s2imag);
s1_non = find(s1real_abs==s1imag_abs)
s2_non = find(s2real_abs==s2imag_abs)

plot(0,0,'g^')

Answer 1

[David Hill]

Really too many points to do an effective scatter plot. Recommend reducing the size of beta.

alpha1 = 3; alpha2 = 1.2; alpha3 = 4; 
beta = -1:1e-3:2;
beta =beta(beta~=0);%removes infinity for an 'a' value
a = (1./beta);
b = (alpha1.*beta.^3) - alpha2;
c = alpha3.*beta;
s1 = (-b + sqrt(b.^2-(4.*a.*c)))./(2.*a);
s2 = (-b - sqrt(b.^2-(4.*a.*c)))./(2.*a);
scatter(real(s1),imag(s1));
hold on;
scatter(real(s2),imag(s2));