max and min values in an array

thank you! Found the solution! Thank you!

[madhan ravi]

findpeaks() ?

[madhan ravi]

So as I understand you want to find the max value for each 16 rows ???

[madhan ravi]

NO NO NO!!!!,Why did you delete all the contents of the question and the comments?, it's a terrible thing to do . Others may also benefit from the question.

Answer 1

[madhan ravi]

See if this does what you want , first we split into 16 separate rows each and then we conquer in the third dimension:

[m,n]=size(A); % where A is your matrix of size 256 X 40K
parts = 16;
AA = permute(reshape(A.',n,m/parts,[]),[2,1,3]);
Max = max(AA,[],[1,2]); % max(max(AA)) for versions <= 2016b
[r,~]=find(AA == Max) % r represents rows 

[Anh Dao]

r,c seems to be wrong, I tried, and there seems to be problem with the split , the row appeared to be all 1, can you please check?

[madhan ravi]

Could you illustrate with a short example? c gives you the linear index unlike r, what do you mean the split is wrong?

>> A = rand(8,2)
[m,n]=size(A); 
parts = 2;
AA = permute(reshape(A.',n,m/parts,[]),[2,1,3]);
Max = max(AA,[],[1,2]); 
[r,~]=find(AA == Max) 

A =

    0.6944    0.9400
    0.3253    0.6584
    0.4368    0.9652
    0.7557    0.0311
    0.4930    0.1461
    0.7457    0.5300
    0.8067    0.8428
    0.9376    0.0922

r =

     3
     4
>> 

[Anh Dao]

I've got this error Product of known dimensions, 40000, not divisible into total number of elements, 15.

[madhan ravi]

256 is divisible by 16 where did you get 15 and why are you bothered with columns now?? We are focused on rows ?

[r,c,p]=ind2sub(size(AA),find(AA==Max)) % r represents rows , c represents columns & p represents pages

Post the code that your trying.

[Anh Dao]

Thank you, so I have a matrix A equal 256x40000

it was a mistake that I put in last time that i put parts = 15, sorry about that, so r should be correct right, what's the difference in the code you posted?

[m,n]=size(A)
parts = 16;
AA = permute(reshape(DoM.',n,m/parts,[]),[2,1,3]);
Max = max(AA,[],[1,2]);
[r,~]=find(AA == Max) 

[madhan ravi]

replace

[r,~]=find(AA == Max) 

with

[r,c,p]=ind2sub(size(AA),find(AA==Max)) % r represents rows , c represents columns & p represents pages