How can I make this work Please? In AccelerationWeek10 (line 10) Index exceeds matrix dimensions. Error in AccelerationWeek10 (line 31) s = s(1:npts/2+1); % truncate (removes complex conjugates)

close all
npts = 2^15;
sfreq = 22150;
dt = 1/sfreq;
t = (0:npts-1)'*dt;
m = 500 % mass
k = 1000000;
c= 1000;
naturalFr = sqrt(k/m)
 sim('week7')% Simulink
figure(1)
plot(Accel)
xlabel('Time [s]')
ylabel('Signal [units]')
s = fft(Accel.Data);%3
figure(2)
subplot(211)
plot(real(s))
grid on
xlabel('Index')
ylabel('Real')
subplot(212)
plot(imag(s))
grid on
xlabel('Index')
ylabel('Real')
% % folding and scaling
Line 31  s = s(1:npts/2+1); % truncate (removes complex conjugates)
s = s/npts; % scale 
s(2:end-1) = 2* s(2:end-1); % fold 6 
df = sfreq/npts;
freq = (0:npts/2)'*df;
mag = abs(s);% 7
% mag1 = sqrt(imag(s).^2+real(s).^2);% 
mag1 = atan(imag(s)/real(s));
figure(3)
plot(freq,mag)
hold on
plot(freq,mag1)
grid on
xlabel('Frequency [Hz]')
ylabel('Magnitude [units]')

[Image Analyst]

Line 10 is

sim('week7')% Simulink

NOT

s = s(1:npts/2+1); % truncate (removes complex conjugates)

Please explain the discrepancy. Please post the actual code you are using because I'm not sure, because of the line number discrepancy, what code you're actually running.

[Stephen Bell]

Line 31 Just under % % folding and scaling

Answer 1

[Walter Roberson]

As outsiders, we have no reason to expect that your call to sim('week7') will produce an Accel.Data that happens to be at least npts/2+1 long.

[Stephen Bell]

How can I fix that please

[Walter Roberson]

You could post your model for week7 so that we could examine it to see what should be expected.