# create a vector filled with random normal values 
u1 <- rnorm(30)
print("This loop calculates the square of the first 10 elements of vector u1") 
usq=0 
iter=1:10 # this can be changed to whatever you need (or just insert 1:10 where iter is in loop)

for(i in iter) 
{ 
 	usq[i]<-u1[i]*u1[i] # i-th element of u1 squared into i-th position of usq 
 	print(usq[i]) 
} 


# nested
mymat = matrix(nrow=30, ncol=30) # create a 30 x 30 matrix (of 30 rows and 30 columns) 
for(i in 1:dim(mymat)[1]) # for each row 
{ 
 	for(j in 1:dim(mymat)[2]) # for each column 
 	{ 
 	   mymat[i,j] = i*j # assign values based on position: product of two indexes 
 	} 
}
i.val=1:5
j.val=1:5
mymat[i.val,j.val]
i.val=1:10
j.val=1:10
mymat[i.val,j.val]
i.val=1:30
j.val=1:30
mymat[i.val,j.val]

# while with a function( )

readinteger <- function() 
{ n <- readline(prompt="Please, enter your ANSWER: ") 
} 
response<-as.integer(readinteger()) 

while (response!=42) 
{ 
 	print("Sorry, the answer to whatever the question MUST be 42");
   	response<-as.integer(readinteger()); 
}

# repeat loop

readinteger <- function() 
{ n <- readline(prompt="Please, enter your ANSWER: ") } 
repeat 
{ 
 	response<-as.integer(readinteger()); 
 	if (response==42) 
 	  { 
 		print("Well done!"); 
 		break 
 	  } 
 	else print("Sorry, the answer to whatever the question MUST be 42"); 
}