Hi, Try:
set.seed(445) A<- matrix(sample(1:20,124*5,replace=TRUE),ncol=5) set.seed(42) B<- matrix(sample(1:25,12*5,replace=TRUE),ncol=5) res<- sapply(seq_len(nrow(A)),function(i) colSums(A[i,]*t(B))) dim(res) #[1] 12 124 A.K. ________________________________ From: eliza botto <eliza_bo...@hotmail.com> To: "smartpink...@yahoo.com" <smartpink...@yahoo.com> Sent: Wednesday, September 11, 2013 11:37 AM Subject: Dear Arun, Thanks for your previous reply. i have another question. if i have to matrix A and matrix B. matrix A is of dimension 124 row * 5 columns and B has a dimension of 12*5. What i want is to multiply each column of matrix B with each element of corresponding column A and then add. more precisely For Row 1 of A A[1,1]*B[,1]+A[1,2]*B[,2]+A[1,3]*B[,3]+A[1,4]*B[,4]+A[1,5]*B[,5] For Row 2 of A A[2,1]*B[,1]+A[2,2]*B[,2]+A[2,3]*B[,3]+A[2,4]*B[,4]+A[2,5]*B[,5] So in the end we should have a matrix of 12 rows and 124 columns. I hope i m clear. if you feel any problem please tell me. Eliza ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
