What LAPACK function is available to calculate 2-norm of a matrix?

[zzzhhh]

What LAPACK function is available to calculate 2-norm (or spectral norm) of a matrix? Thank you.

[Gennady_F_Intel]

look at ?nrm2 routines, where ? == [s,d,c,z]

[zzzhhh]

That's BLAS level 1 routine, for vector norm only. But I was asking about matrix norm in LAPACK.

[Nadezhda_M_Intel]

In LAPACK we have ?lange for general matrix and ?lan[sy/he] for symmetric matrices. Using these functions you can get: 1-norm, Frobenius and infinity norms.

[Nadezhda_M_Intel · Accepted solution]

Unfortunately in LAPACK we don't have function for 2-norm.

Computations of spectral norm is very time-consuming task. Using "F" norm from ?lange function you can get fast upper estimation.

[zzzhhh]

Thanks, Nadezhda Mozartova. I have to use 2-norm. This is not something I have control over.