Delay and Sum example error

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Dhananjay Singh
Dhananjay Singh on 7 Mar 2019
Answered: Astha Singh on 14 Mar 2019
Hi, I'm very new to MATLAB and am having some trouble. I am running an example i found online but I am facing this problem. Could somebody please explain what this error is and how to fix it.
The code i am running is :
xPos = -0.8:0.2:0.8; % 1xP vector of x-positions [m]
yPos = zeros(1, numel(xPos)); % 1xP vector of y-positions [m]
zPos = zeros(1, numel(xPos));
elementWeights = ones(1, numel(xPos))/numel(xPos); % 1xP vector of weightings
% Define arriving angles and frequency of input signals
thetaArrivalAngles = [-30 10]; % degrees
phiArrivalAngles = [0 0]; % degrees
f = 800; % [Hz]
c = 340; % [m/s]
fs = 44.1e3; % [Hz]
% Define array scanning angles (1D, so phi = 0)
thetaScanAngles = -90:0.1:90; % degrees
phiScanAngles = 0; % degrees
% Create input signal
inputSignal = createSignal(xPos, yPos, zPos, f, c, fs, thetaArrivalAngles, phiArrivalAngles);
% Create steering vector/matrix
e = steeringVector(xPos, yPos, zPos, f, c, thetaScanAngles, phiScanAngles);
% Create cross spectral matrix
R = crossSpectralMatrix(inputSignal);
% Calculate delay-and-sum steered response
S = steeredResponseDelayAndSum(R, e, elementWeights);
%Normalise spectrum
spectrumNormalized = abs(S)/max(abs(S));
%Convert to decibel
spectrumLog = 10*log10(spectrumNormalized);
%Plot array
fig1 = figure;
fig1.Color = 'w';
ax = axes('Parent', fig1);
scatter(ax, xPos, yPos, 20, 'filled')
axis(ax, 'square')
ax.XLim = [-1 1];
ax.YLim = [-1 1];
grid(ax, 'on')
title(ax, 'Microphone positions')
%Plot steered response with indicator lines
fig2 = figure;
fig2.Color = 'w';
ax = axes('Parent', fig2);
plot(ax, thetaScanAngles, spectrumLog)
grid(ax, 'on')
ax.XLim = [thetaScanAngles(1) thetaScanAngles(end)];
for j=1:numel(thetaArrivalAngles)
indx = find(thetaScanAngles >= thetaArrivalAngles(j), 1);
line(ax, [thetaScanAngles(indx) thetaScanAngles(indx)], ax.YLim,'LineWidth', 1, 'Color', 'r', 'LineStyle', '--');
end
xlabel(ax, '\theta')
ylabel(ax, 'dB')
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
The error that i face is :
Vectors must be the same length.
Error in examplesSteeredResponse
line(ax, [thetaScanAngles(indx) thetaScanAngles(indx)], ax.YLim,'LineWidth', 1, 'Color', 'r', 'LineStyle', '--');
Can somebody please tell me what should I do to reolve this issue.

Answers (1)

Astha Singh
Astha Singh on 14 Mar 2019
As the error is reported in the usage of the 'line()' command, you should refer to the documentation page of the same (link provided below), and see if the variables that are being plotted are in the expected form.
The 'line(x,y)' function requires the x and y co-ordinate values, it plots the variable 'y' against 'x'. Hence both should be of the same length. Please confirm that is also the case with the variables you are plotting.

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