matrix dimension and for loop

Dear all,

My questions are that if I have

x<-rnorm(50)
dim(x)<-c(10,5)
y=1:5
Z<-matrix(0,NROW(x),NROW(y))
for (j in 1:NROW(y)) Z[,j]<-x[,j]*y[j]

1. Is there any other way to write this without 'for'
loop?

2. and if I don't know the dimension of x, which could
be only 1 column, how could I write the command
without using if (NCOL(x)==1), or something like that?
(in case I want to include them in my function.

Example of x is a vector.

x<-rnorm(10)
y=2
Z<-matrix(0,NROW(x),NROW(y))
for (j in 1:NROW(y)) Z[,j]<-x[,j]*y[j]

Error in x[, j] : incorrect number of dimensions

Could anyone please help me to solve these problem? 
Thank you very much for your kindness.


Sonchawan Tamkaew 

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