R: matrix by vector multiplication

Question

I have following problem:

myvec <- c(1:3)

mymat <- as.matrix(cbind(a = 6:15, b = 16:25, c= 26:35))
mymat
       a  b  c
 [1,]  6 16 26
 [2,]  7 17 27         


        

Answer 1

Matrices are vectors in column major order:

 colSums(  t(mymat) * myvec )  

(Edited after hopefully reading question correctly this time.)