Give me an hint

Hi,

I just need a hint of how to do a homework problem. Suppose I have this data: time = [1 2 3 4 5 6 7 8 9 10 11 12 13]' spike = [0 0 0 1 1 0 1 0 0 0 1 1 0]' Let me explain this. The zeros and ones indicate the presence and absence of spike, with zero being no spike and one being there is a spike. The time are in milliseconds and it corresponds to the spike. For example: there was a spike at 4msecs, 5 msecs, 7 msecs, 11msec and 12 msecs. The homework problem is to make a program to find the time in which the third spike occurred? The homework strictly states no loops allowed. Thank you

Answer 1

[James Tursa]

Hint:

doc find

Answer 2

[Chad Greene]

Here's a hint. Run this:

% some data: 
time = 1:20; 
y = [1 1 0 2 3 4 3 5 6 4 3 12 3 5 4 7 4 11 15 4]; 

% Indices of all fours: 
fours = find(y==4); 

% Index of the third four: 
thirdfour = fours(3); 

% Time of third four: 
time(thirdfour) 

% plot all data: 
plot(time,y,'bo')

% plot fours as red X marks:
hold on
plot(time(fours),y(fours),'rx') 
xlabel('time') 
box off