A guess that j and k should change together, from (j=3 & k=1) to (j=4 and k=2). If so, this would be a solution:

pearson = matrix(nrow = 2, ncol = 2)

for(i in 1:2) {

for(k in 1:2) {

j = k+2

pearson[i, k] = cor(iris[i], iris[j])

}

}

print(pearson)

[,1] [,2]

[1,] 0.8717538 0.8179411

[2,] -0.4284401 -0.3661259

Agree with Mr Sampath, the best way is to use cor(). But, if you want make this loop,

Pearson = matrix(nrow = 2, ncol = 2)

for(i in 1:2){

for(j in 3:4){

for(k in 1:2){

pearson[i, k] = cor(iris[i], iris[j])

}}}

I think the "&&" cannot be use in "for loop", but only in conditions ...

@Mr. Sampath ... Thank you for the answer. This was almost out of my mind. Im Bioinfo student and totally new to R. Can you explain what tht two sentences mean ?

@Jochen Wilhelm. Thanks a lot :) You gave me a totally new point to think on everytime I do programming.

@Anne-Hélène Rêve

Thank you for the answer.

I tried this but it didnt work. Thats why I thought to put it in the same for statement but without any fruitful results.

I had a misconception that cor function takes 2 variables as input but yes it can take a matrix as argument too. I understood after I tried with other matrices.