Let v in R^m and let J be a matrix from R^n to R^m, with m>n big numbers.
I want to compute the projection w of v on the image of J.
For computing the projection on the image of J, we can do as follows : JTGS=J.transpose().gram_schmidt()[0] p=JTGS.transpose()*JTGS
Then: w=p*v
But this method is very expensive in time, because it computes p, while I just need w.
Is there another method, less expensive in time, for computing w ?