I have a large collection of vectors, each of the form [a,b,c,d].
For each vector, I want to return the result [a,b,c,d,a+b^2+c^3+d^4]. What would be the best way of doing this?
For example, say my vectors are V = [ [1,2,3,4], [5,6,7,8], [9, 10, 11, 12] ]. Would the best way to do this be defining a function such as:
test( W ) = for( i=1, #W, print( [ [W[i][1],W[i][2],W[i][3],W[i][4],W[i][1]+W[i][2]^2+W[i][3]^3+W[i][4]^4] ] ) ) ?
(Keeping in mind that in practice I will also have a larger collection of vectors)
This feels like a naive way of doing this, so is there a better way? In particular, is this the quickest way? Is there a better way to store my collection of vectors?
Use matrix to store the vector of vectors. Then just append the new column containing the sum of your exponentials. See the example:
V = [[1,2,3,4], [5,6,7,8], [9, 10, 11, 12]]; /* your vector of vectors */
M = matconcat([V[1]; V[2]; V[3]]);
M_log = log(M);
matconcat([M, M[,1] + exp(2*M_log[,2]) + exp(3*M_log[,3]) + exp(4*M_log[,4])])
> [1 2 3 4 288.00]
> [5 6 7 8 4480.00]
> [9 10 11 12 22176.00]