Matlab out of memory. Error using pdistmex

Question

I have a matrix M of size(262322x4). On running knn imputation:

M=csvread("C:\Users\Hello\Desktop\DATA\B.csv",1,0);
B = transpose(M);
A = knnimpute(B,1);
C=transpose(A);

I get the following error:

>>knn_imputation
Error using pdistmex
Out of memory. Type HELP MEMORY for your options.

Error in pdist (line 264)
Y = pdistmex(X',dist,additionalArg);

Error in knnimpute (line 162)
distances = pdist(dataNoNans',metric,distargs{:});

Error in knn_imputation (line 4)
A = (knnimpute(B,1));

Is this error due to Memory limitations or something else?

(Note: Memory size: 8GB)