Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
Drexel University or The Math Forum.


dpb
Posts:
9,242
Registered:
6/7/07


Re: Indexing
Posted:
Mar 6, 2013 1:02 PM


On 3/5/2013 9:16 PM, Eric wrote: > Hi, > > I know I should be able to figure this out based on previous posts, but > I still cannot find the correct solution. Within matrix A (nx1 matrix), > I want to find the first instance that a value BW is 10 units less than > BWI'll call this value DROP. It is not a min or max value. I am just > trying to index points on a force waveform so I can eventually integrate > the area between points. > > Specifically: > BW= 650; DROP = BW10; > [event1,ind1] = A(DROP,1); > > Using this, I get an error 'Indexing cannot yield multiple results'. > I tried using find but all the values will be positive numbers. ...
ix=find(A==DROP,1); % the first index A(ix) % the value at that index
NB: If A is floating point and not integervalue, the problem of exact comparisons for floating point values may rear its head...the values you've shown are integers well withing DP resolution so will be stored exactly, but that's not necessarily so in general of course.




