Unable to perform assignment because the size of the left side is 1-by-3 and the size of the right side is 7-by-3.

i am trying to simulate 3D medium with source and detector in matlab using TOAST. i am getting following error,

Unable to perform assignment because the size of the left side is 1-by-3 and the size of the right side is

7-by-3.

Error in demo3d (line 53)

Q(2,:) = r1 * [sin(t1)*cos(p1) sin(t1)*sin(p1) cos(t1)];

the code is follows,

clear all
close all

%% Geo parameters
r1 = 12;
nd = 1;
rfac = 0.25;
r2 = r1*rfac;
x = 0.4;
y = 0.4%5;
z = 0%-5;
x = r1*x;
y = r1*y;
z = r1*z;
%% Create the mesh/Load the mesh
mesh = toastMesh('sphere_test_toast.msh');
figure (1)
%mesh.Display

freq = 0; % modulation frequency [MHz] %0 for CW system

%% Create the background parameters
muaB = 0.01;
musB = 1.0;
refrec = 1.4;
nodes = mesh.Data;

figure (2)
scatter3(nodes(:,1),nodes(:,2),nodes(:,3),20,'filled');

nodesB = nodes(sqrt((nodes(:,1)-x).^2+(nodes(:,2)-y).^2+(nodes(:,3)-z).^2)>r2,:);
mua = ones(size(nodes,1),1).*muaB;
mus = ones(size(nodes,1),1).*musB;
ref = ones(size(nodes,1),1).*refrec;

figure (3)
scatter3(nodes(:,1),nodes(:,2),nodes(:,3),20,mua,'filled');
ax = gca;
view(-36.5,16)
cb = colorbar;

figure (4)
scatter3(nodes(:,1),nodes(:,2),nodes(:,3),20,mus,'filled');
ax = gca;
view(-36.5,16)
cb = colorbar;

%% Placing the S/D

t1 = 0; p1 = 0;
Q(1,:) = r1 * [sin(t1)*cos(p1) sin(t1)*sin(p1) cos(t1)];
t1 = pi; p1 = 0;
Q(2,:) = r1 * [sin(t1)*cos(p1) sin(t1)*sin(p1) cos(t1)];


t2 = 2*pi/4; p2 = 0;
D(1,:) = r1 * [sin(t2)*cos(p2) sin(t2)*sin(p2) cos(t2)];
t3 = t2; p3 = pi/2;
D(2,:) = r1 * [sin(t3)*cos(p3) sin(t3)*sin(p3) cos(t3)];
t4 = t2; p4 = pi;
D(3,:) = r1 * [sin(t4)*cos(p4) sin(t4)*sin(p4) cos(t4)];
t5 = t2; p5 = 3*pi/2;
D(4,:) = r1 * [sin(t5)*cos(p5) sin(t5)*sin(p5) cos(t5)];


%% Visualize the mesh with S-D
mesh.SetQM(Q,D);
ShowD = [1,3,4];

figure (5)
mesh.Display()
s1 = scatter3(nodesB(:,1),nodesB(:,2),nodesB(:,3),20,'filled','MarkerFaceColor','b');
alpha(s1,.2)
ax = gca;
view(-36.5,16)
cb = colorbar;   
hold on
scatter3(Q(:,1),Q(:,2),Q(:,3),'ro','MarkerFaceColor','y');
scatter3(D(ShowD,1),D(ShowD,2),D(ShowD,3),'ro','MarkerFaceColor','r');

%% Solve the forward problem

qvec = mesh.Qvec('Neumann', 'Gaussian', 2);
mvec = mesh.Mvec('Gaussian', 2,0);


K = dotSysmat(mesh,mua,mus,ref,freq);
Phi = K\qvec;
Y = mvec.' * Phi;
logY = log(Y);
lnamp = real(logY);
phase = imag(logY);

figure (6)
hold on
angle = [90:360/4:360];
for i=1:size(lnamp,2)
    ywrap = [lnamp(i:end,i); lnamp(1:i-1,i)];
    plot(angle,ywrap,'o-');
end
axis([0 360 -14 -2]);
xlabel('angular source-detector separation');
ylabel('log intensity');

kindly help me.

[Jan]

Please use the tools to format your code. The easier the code is to read, the more likely is a useful answer.

Answer 1

[Jan]

"Unable to perform assignment because the size of the left side is 1-by-3 and the size of the right side is 7-by-3."

This error message cannot be produced by this code:

r1 = 12;
...
t1 = pi; p1 = 0;
Q(2,:) = r1 * [sin(t1)*cos(p1) sin(t1)*sin(p1) cos(t1)];

This means, that you did not post the failing code but another one. Then the readers do not have a change to guessm what the problem is.

Use the debugger to find out, which code is actually failing:

dbstop if error

Type this in the command window, start the code and see, where Matlab stops. Now you can check the dimensions of the variables used in this line.