I want to generate different combinations of amplitudes. let say 10k random combinations. i am new to matlab, anyone who can help, how to generate it.

clear all;

clc;

f0=1/(2*pi);%initial frequency of dipoles

% x_probe=5;%x coordinates of reciever point

% y_probe=5;%x coordinates of reciever point

N=400; % number of dipoles in the area

a = 0.5; % width along x

b = 0.5; % height along y

x=a*rand(1,N); % random coordinates of dipoles

y=b*rand(1,N);

xmin=0;xmax=0.5;

ymin=0;ymax=0.5;

Xpoints=400;Ypoints=400;

xg=linspace(xmin,xmax,Xpoints);yg=linspace(ymin,ymax,Ypoints);

[Xi,Yi]=meshgrid(xg,yg);

Rx=reshape(Xi,[length(xg)*length(yg) 1]);

Ry=reshape(Yi,[length(xg)*length(yg) 1]);

amp(1:N)=0;% amplitude of emmiting dipoles

amp(1)=1; % 2 dipoles emitting (relative amplitude)

amp(2)=0.75;

amp(3)=0.5;

amp(4)=0.5;

amp(5)=1;

x(1)=0; % x coordinates of 1 dipole that emits

y(1)=0.05; % y coordinates of 1 dipole that emits

x(2)=0; % x coordinates of 1 dipole that emits

y(2)=0.10; % y coordinates of 2nd dipole that emits

x(3)=0;

y(3)=0.15;

x(4)=0;

y(4)=0.20;

x(5)=0;

y(5)=0.25;

x_probe=5;%x coordinates of reciever point

y_probe=3.5;%x coordinates of reciever point

x_probe1=5;

y_probe1=2.5;

x_probe2=5;

y_probe2=1.5;

x_probe3=5;

y_probe3=0.5;

%resonant freq and external excitation set

fres(1:N)=f0;%constant resonant frequency

loss = 0;

rw(1:N)=loss; % absorption losses

% frequency steps selected

fmin=0.2;fmax=1.3;fstep=(fmax-fmin)/401;

f_mult=fmin:fstep:fmax; % frequency range (multiplier)

f=f_mult*f0; % frequency range

scatter(x,y,'rv','filled')

hold on

scatter(x_probe,y_probe,'gs','filled')

scatter(x_probe1,y_probe1,'gs','filled')

scatter(x_probe2,y_probe2,'gs','filled')

scatter(x_probe3,y_probe3,'gs','filled')

scatter(x(1:5),y(1:5),'bo','filled')

hold off

Answer 1

[Nehemiae]

Hello,

To generate a random set of amplitudes, the “rand” function can be used. This generates a random number from the uniform distribution in the interval (0, 1), which is essentially what is needed as it is the relative amplitude. The number of random numbers generated depends on the matrix dimensions given to the function, which can be (1, N) to generate N random numbers.

N = 400; % Number of dipoles in the area 

% Random coordinates of dipoles 
x = a * rand(1, N);  
y = b * rand(1, N); 

amp = rand(1, N); % Amplitude of emmiting dipoles 

% Random coordinates of reciever point 
x_probe = a * rand(1, N);  
y_probe = b * rand(1, N); 

scatter(x, y, 'rv', 'filled') 
hold on 
scatter(x_probe, y_probe, 'gs', 'filled') 
hold off

The documentation on “rand” function (https://www.mathworks.com/help/matlab/ref/rand.html) is helpful in this regard.