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Dear R-ians, I am trying to do an endmember unmixing. For this process I need to define my endmembers (= the extremes of a 3D or 2D cloud). Is there anyone who has advice on how to automatically extract those...

Thank you very much Ted! I have been looking at your simplification for more then an hour, but I don't see how you did it. Could you perhaps, if it is not to much work, explain me how you...

Dear Christoph, Thanks for your help! I checked it in R and it works if we extend a and b with one element for each run. Unfortunately, I actually want to merge two vectors and then calculate the H for...

Dear R-ians, I am working with princomp and I now want to manually recalculate my original values. I want to do it to completely understand the procedure of principal components. I tried it with a test data set (2...

Dear R-ians, I have a datamatrix X of nrows (large) and 3 colums. The 3 columns represent the coordinates of a cloud in a 3 dimensional space. Now I want to find the extremes of my cloud by using...

Dear R-ians, I want to perform an linear unmixing of image pixels in fractions of pure endmembers. Therefore I need to perform a constrained linear least-squares problem that looks like : min || Cx - d || ? where sum(x) = 1. I...

Thanx Dimitris, Patrick and Berwin! For other people interested in this problem, here are two valid solutions that work. 1) Re-parameterize e.g., EM <- c(100,0,0,0,100,0,0,0,100) W <- array(EM, c(3...

Dear R-ians, I have a question concerning plotting different plots on one figure. I have written a script to plot an image, a legend (based on different rectangles) and a timeseries plot on one figure. In my R-lagnuage...

Dear R-ians, I'm looking for a computational simplified formula to calculate a measure for heterogeneity (let's say H ): H = sqrt [ (Si (Sj (Xi - Xj)?? ) ) /n ] where: sqrt = square root Si = summation over i (= 0 to n) Sj...

Dear R-ians, I am looking for the simplification of a formula to improve the calculation speed of my program. Therefore I want to simplify the following formula: H = Si (Sj ( sqrt [ (Ai - Aj)?? + (Bi - Bj)?? ] ) ) where: A, B = two...

Dear, I am looking for the simplification of a formula to improve the calculation speed of my program. Therefore I want to simplify the following formula: H = sum{i=0..n-1 , [ sum {j=0..m-1 , sqrt ( (Ai - Bj...