REAL FUNCTION SNRM2 ( N, X, INCX ) * .. Scalar Arguments .. INTEGER INCX, N * .. Array Arguments .. REAL X( * ) * .. * * SNRM2 returns the euclidean norm of a vector via the function * name, so that * * SNRM2 := sqrt( x'*x ) * * * * -- This version written on 25-October-1982. * Modified on 14-October-1993 to inline the call to SLASSQ. * Sven Hammarling, Nag Ltd. * * * .. Parameters .. REAL ONE , ZERO PARAMETER ( ONE = 1.0E+0, ZERO = 0.0E+0 ) * .. Local Scalars .. INTEGER IX REAL ABSXI, NORM, SCALE, SSQ * .. Intrinsic Functions .. INTRINSIC ABS, SQRT * .. * .. Executable Statements .. IF( N.LT.1 .OR. INCX.LT.1 )THEN NORM = ZERO ELSE IF( N.EQ.1 )THEN NORM = ABS( X( 1 ) ) ELSE SCALE = ZERO SSQ = ONE * The following loop is equivalent to this call to the LAPACK * auxiliary routine: * CALL SLASSQ( N, X, INCX, SCALE, SSQ ) * DO 10, IX = 1, 1 + ( N - 1 )*INCX, INCX IF( X( IX ).NE.ZERO )THEN ABSXI = ABS( X( IX ) ) IF( SCALE.LT.ABSXI )THEN SSQ = ONE + SSQ*( SCALE/ABSXI )**2 SCALE = ABSXI ELSE SSQ = SSQ + ( ABSXI/SCALE )**2 END IF END IF 10 CONTINUE NORM = SCALE * SQRT( SSQ ) END IF * SNRM2 = NORM RETURN * * End of SNRM2. * END