I have same values for all the 3 matrices

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Balaji Ramdas
Balaji Ramdas 2021-11-3
编辑： Rik 2021-11-28
All the 3 matrices should show a diffent values but i get to see all are the same with a warning stating " The variable XXXX appeaqrs to change the sign on every loop iteration"
Here is the code:
for m=1:length(y)
for n=1:length(x)
r1source(m,n)=sqrt((x(n)-x1)^2+(y(m)-y1)^2);
r2source(m,n)=sqrt((x(n)-x2)^2+(y(m)-y2)^2);
r3source(m,n)=sqrt((x(n)-x3)^2+(y(m)-y3)^2);
end
end
  1 个评论
Rik
Rik 2021-11-3
Without input data I don't see why the resulting matrices would be te same, nor where the warning would be coming from.
This can probably be done without a loop anyway, and if is can't you should replace length with numel, since that is probably what you mean.

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回答（1 个）

KSSV
KSSV 2021-11-3
You need to initialize the variables which store data inside the for loop.
% Initilization
r1source = zeros(length(y),length(x)) ;
r2source = zeros(length(y),length(x)) ;
r3source = zeros(length(y),length(x)) ;
% loop
for m=1:length(y)
for n=1:length(x)
r1source(m,n)=sqrt((x(n)-x1)^2+(y(m)-y1)^2);
r2source(m,n)=sqrt((x(n)-x2)^2+(y(m)-y2)^2);
r3source(m,n)=sqrt((x(n)-x3)^2+(y(m)-y3)^2);
end
end
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KSSV
KSSV 2021-11-3
Thanks is accepting/ voting the answer. :)
Balaji Ramdas
Balaji Ramdas 2021-11-28
编辑：Rik 2021-11-28
Just another question, how do i create the meausrement plane into imaginary ? as source plane the z axis value is zero but for the measurement plane it has to be an imaginary plane with z axis value of 0.2 from the real plane
%%source's positions
% source 1
x1=0.4;
y1=0.2;
z1=0;
%source 2
x2=0.8;
y2=0.55;
z2=0.2;
%source 3
x3=0.5;
y3=0.65;
z3=0.5;
f=1000; %Hz frequency
A1=1; %amplitude
w=2*pi*f; % angular speed
c=343; %m/s speed of sound in air
lambda=c/f; %m wave length
k0=w/c; %wave number
s=20; %matrix size
j=0.00001; % imaginary part
pref=2*10^-5; %Pa
p0=1.275; %kg/m3 air density
%aperture or Matrix size
x=linspace(1,0,s);
y=linspace(1,0,s);
z=linspace(1,0,s);
%Source plane
% Initilization
r1source = zeros(length(y),length(x),length(z)) ;
r2source = zeros(length(y),length(x),length(z)) ;
r3source = zeros(length(y),length(x),length(z)) ;
for m=1:length(y)
for n=1:length(x)
for o=1:length(z)
r1source(m,n,o)=sqrt((x(n)-x1)^2+(y(m)-y1)^2+(z(o)-z1)^2);
r2source(m,n,o)=sqrt((x(n)-x2)^2+(y(m)-y2)^2+(z(o)-z2)^2);
r3source(m,n,o)=sqrt((x(n)-x3)^2+(y(m)-y3)^2+(z(o)-z3)^2);
end
end
end
%Measurement plane
% Initilization
r1measurement = zeros(length(y),length(x),length(z)) ;
r2measurement = zeros(length(y),length(x),length(z)) ;
r3measurement = zeros(length(y),length(x),length(z)) ;
for m1=1:length(y)
for n1=1:length(x)
for o1=1:length(z)
r1measurement(m1,n1,o1)=sqrt((x(n1)-x1)^2+(y(m1)-y1)^2+(z(o1)-z1)^2);
r2measurement(m1,n1,o1)=sqrt((x(n1)-x2)^2+(y(m1)-y2)^2+(z(o1)-z2)^2);
r3measurement(m1,n1,o1)=sqrt((x(n1)-x3)^2+(y(m1)-y3)^2+(z(o1)-z3)^2);
end
end
end

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