Array indices must be positive integers or logical values

So I am trying to create an easy function to calculate an equation for all the values between 0 and 90 degrees, in order to create a plot of the Earth dipole field for different altitudes, but I keep getting the same error message:

Array indices must be positive integers or logical values.

I have tried different approaches, but I am not able to make it work. If I don't store the values for the plot, the loop runs and gives me the correct values, but the moment I try to store them to plot them all together, it gives me the error. Can somebody help?

%% MAGNETORQUER SIZING

clear all; clc;

%% Magnitude of the Dipole Field:

nu0 = 1.256637*10^-6;   % [H/m]  Permeability of free space
m = 8*10^22;            % [A m2] Earth's magnetic dipole moment

h = 400;                % Altitude in [km]
r = 6378 + h;           % Orbit radius in [km]
rm = r*1000;            % Scaling to [m]

for i = 0:0.1:90
    
    B = (nu0/(4*pi))*(m/rm^3)*sqrt(1+3*sind(i)^2);
    Bplot(i) = B;
    
end

figure(1);
grid on; hold on;
plot(B,i,'b-','Displayname','Magnitude of the dipole field');

Answer 1

[Alex Mcaulley]

You are trying to acces to: B(0), B(0.1) and so on, which are not allowed indexes. Try with this:

%% MAGNETORQUER SIZING
clear all; clc;
%% Magnitude of the Dipole Field:
nu0 = 1.256637*10^-6;   % [H/m]  Permeability of free space
m = 8*10^22;            % [A m2] Earth's magnetic dipole moment
h = 400;
r = 6378 + h;
rm = r*1000;
i = 0:0.1:90
    
Bplot = (nu0/(4*pi))*(m/rm^3)*sqrt(1+3*sind(i).^2);
    
figure(1);
grid on; hold on;
plot(Bplot,i,'b-','Displayname','Magnitude of the dipole field');

[Ignacio Vinuela]

Thanks Alex!

It worked as I wanted