REAL FUNCTION SNRM2(N,SX,INCX)
 
a real function that computes the Euclidean norm of a real
vector, also known as the root-mean-square norm, or the square root
of the sum of the squares of the entries.
 
N      Input, INTEGER N, number of elements in vector.
 
SX     Input, REAL SX(N), the vector whose norm is to be taken.
 
INCX   Input, INTEGER INCX, increment between elements of SX.  For contiguous
       elements, INCX = 1.
 
SNRM2  Output, REAL SNRM2, the Euclidean norm of SX.