double precision function bnorm (n, a, nra, ml, mu, w) clll. optimize c----------------------------------------------------------------------- c this function computes the norm of a banded n by n matrix, c stored in the array a, that is consistent with the weighted max-norm c on vectors, with weights stored in the array w. c ml and mu are the lower and upper half-bandwidths of the matrix. c nra is the first dimension of the a array, nra .ge. ml+mu+1. c in terms of the matrix elements a(i,j), the norm is given by.. c bnorm = max(i=1,...,n) ( w(i) * sum(j=1,...,n) abs(a(i,j))/w(j) ) c----------------------------------------------------------------------- integer n, nra, ml, mu integer i, i1, jlo, jhi, j double precision a, w double precision an, sum dimension a(nra,n), w(n) an = 0.0d0 do 20 i = 1,n sum = 0.0d0 i1 = i + mu + 1 jlo = max0(i-ml,1) jhi = min0(i+mu,n) do 10 j = jlo,jhi 10 sum = sum + dabs(a(i1-j,j))/w(j) an = dmax1(an,sum*w(i)) 20 continue bnorm = an return c----------------------- end of function bnorm ------------------------- end