Subscript indices must either be real positive integers or logicals.
in [Matlab]
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From: Sow-Mun Chan on 20 Jan 2010 19:35 Hi, I have found many threads that had the same problem. Unfortunately, I am not that familiar with Matlab so I wasn't able to fix it. My wrote represents the ear, and what the neurons do when a signal gets through - there will be a spike. I have a few loops in it, that count how often a signal gets through, etc. Now I want to draw a period histogram that shows me at what phase of the sine wave the most spikes are. I've written the code and now it tells me "Subscript indices must either be real positive integers or logicals." The error is in the line y = a * sin (x) + b * (randn(1,length(x))); Can anybody help me with this issue? Thank you in advance. Sow-Mun d = 10; x = 1:(1/d):300; a = 1; b = 2; f = 1000; %f = frequency y = a * sin (x) + b * (randn(1,length(x))); %sine wave with amplitude a, noise with size b count = zeros(1,100); period = zeros(1,60); for j = 1:100 c=0.002; %c=refractory period5 k=zeros(1,length(x)); %d needed due to 0.1 steps for i = 1:length(x) c=c+((1/(f*d))/(2*pi)); %time step if y(i)>1 && c>=0.002 k(i)=1; % if y(i)>1 and the refractory period is equal to to or bigger than % 0.002 then a signal is detected c=0; end end c = sum (k); count(c+1) = count(c+1) + 1; phase = 0; k = find(k); %find positions of spikes for v = 1:length(k) phase(v) = mod(x(k(v)), 2*pi); %find x-value at position of spike end bins = round(phase/(2*pi)*60); %round the number to integer so they can be allocated to a bin bins = bins(bins > 0); %remove all zeros for length = 1:length(bins) period(bins(length)) = period(bins(length)) + 1; end end count time = x*(1/f)/(2*pi); plot (time, y) figure plot (time, k) figure plot(time, y, time, k, 'red' ); xlabel('time') ylabel('amplitude') figure plot(period, '.');
From: Nathan on 20 Jan 2010 19:58 On Jan 20, 4:35 pm, "Sow-Mun Chan" <sow.c...(a)warwick.ac.uk> wrote: > Hi, I have found many threads that had the same problem. Unfortunately, I am not that familiar with Matlab so I wasn't able to fix it. My wrote represents the ear, and what the neurons do when a signal gets through - there will be a spike. I have a few loops in it, that count how often a signal gets through, etc. Now I want to draw a period histogram that shows me at what phase of the sine wave the most spikes are. > I've written the code and now it tells me "Subscript indices must either be real positive integers or logicals." The error is in the line y = a * sin (x) + b * (randn(1,length(x))); > Can anybody help me with this issue? > Thank you in advance. > > Sow-Mun > > d = 10; > x = 1:(1/d):300; > a = 1; > b = 2; > f = 1000; > %f = frequency > > y = a * sin (x) + b * (randn(1,length(x))); > %sine wave with amplitude a, noise with size b > > count = zeros(1,100); > period = zeros(1,60); > > for j = 1:100 > > c=0.002; > %c=refractory period5 > k=zeros(1,length(x)); > > %d needed due to 0.1 steps > for i = 1:length(x) > > c=c+((1/(f*d))/(2*pi)); > %time step > > if y(i)>1 && c>=0.002 > > k(i)=1; > % if y(i)>1 and the refractory period is equal to to or bigger than > % 0.002 then a signal is detected > c=0; > end > > end > > c = sum (k); > count(c+1) = count(c+1) + 1; > > phase = 0; > k = find(k); > %find positions of spikes > for v = 1:length(k) > phase(v) = mod(x(k(v)), 2*pi); > %find x-value at position of spike > end > > bins = round(phase/(2*pi)*60); > %round the number to integer so they can be allocated to a bin > bins = bins(bins > 0); > %remove all zeros > > for length = 1:length(bins) > period(bins(length)) = period(bins(length)) + 1; > > end > > end > > count > time = x*(1/f)/(2*pi); > plot (time, y) > figure > plot (time, k) > figure > plot(time, y, time, k, 'red' ); > xlabel('time') > ylabel('amplitude') > figure > plot(period, '.'); Your problem seems that your code is riddled with errors. One major thing you need to notice: You created a variable called length within one of your loops. Doing so, you can no longer use the function LENGTH within your mfile. NEVER USE FUNCTION NAMES AS VARIABLES. I cannot stress that enough. Change this, and then go through your code to see what you want done. Another error I see is that you are trying to index your variable count by a non-integer variable c. As the error you give mentions, you can only index arrays by POSITIVE INTEGERS or LOGICALS. After you sort these two errors out, try debugging the rest for yourself, as I don't know what you want to do with the other errors that pop up. -Nathan
From: TideMan on 20 Jan 2010 22:10 On Jan 21, 1:58 pm, Nathan <ngrec...(a)gmail.com> wrote: > On Jan 20, 4:35 pm, "Sow-Mun Chan" <sow.c...(a)warwick.ac.uk> wrote: > > > > > Hi, I have found many threads that had the same problem. Unfortunately, I am not that familiar with Matlab so I wasn't able to fix it. My wrote represents the ear, and what the neurons do when a signal gets through - there will be a spike. I have a few loops in it, that count how often a signal gets through, etc. Now I want to draw a period histogram that shows me at what phase of the sine wave the most spikes are. > > I've written the code and now it tells me "Subscript indices must either be real positive integers or logicals." The error is in the line y = a * sin (x) + b * (randn(1,length(x))); > > Can anybody help me with this issue? > > Thank you in advance. > > > Sow-Mun > > > d = 10; > > x = 1:(1/d):300; > > a = 1; > > b = 2; > > f = 1000; > > %f = frequency > > > y = a * sin (x) + b * (randn(1,length(x))); > > %sine wave with amplitude a, noise with size b > > > count = zeros(1,100); > > period = zeros(1,60); > > > for j = 1:100 > > > c=0.002; > > %c=refractory period5 > > k=zeros(1,length(x)); > > > %d needed due to 0.1 steps > > for i = 1:length(x) > > > c=c+((1/(f*d))/(2*pi)); > > %time step > > > if y(i)>1 && c>=0.002 > > > k(i)=1; > > % if y(i)>1 and the refractory period is equal to to or bigger than > > % 0.002 then a signal is detected > > c=0; > > end > > > end > > > c = sum (k); > > count(c+1) = count(c+1) + 1; > > > phase = 0; > > k = find(k); > > %find positions of spikes > > for v = 1:length(k) > > phase(v) = mod(x(k(v)), 2*pi); > > %find x-value at position of spike > > end > > > bins = round(phase/(2*pi)*60); > > %round the number to integer so they can be allocated to a bin > > bins = bins(bins > 0); > > %remove all zeros > > > for length = 1:length(bins) > > period(bins(length)) = period(bins(length)) + 1; > > > end > > > end > > > count > > time = x*(1/f)/(2*pi); > > plot (time, y) > > figure > > plot (time, k) > > figure > > plot(time, y, time, k, 'red' ); > > xlabel('time') > > ylabel('amplitude') > > figure > > plot(period, '.'); > > Your problem seems that your code is riddled with errors. > > One major thing you need to notice: > You created a variable called length within one of your loops. > Doing so, you can no longer use the function LENGTH within your mfile. > NEVER USE FUNCTION NAMES AS VARIABLES. > I cannot stress that enough. > Change this, and then go through your code to see what you want done. > > Another error I see is that you are trying to index your variable > count by a non-integer variable c. As the error you give mentions, you > can only index arrays by POSITIVE INTEGERS or LOGICALS. > > After you sort these two errors out, try debugging the rest for > yourself, as I don't know what you want to do with the other errors > that pop up. > > -Nathan Nathan: Yes, I think he's defined sin as a variable as well. One thing to do to get going is to put: clear all at the top of your script. This will remove all the horrors you've introduced in previous runs.
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