REAL FUNCTION SCNRM2( N, X, INCX ) * .. Scalar Arguments .. INTEGER INCX, N * .. Array Arguments .. COMPLEX X( * ) * .. * * SCNRM2 returns the euclidean norm of a vector via the function * name, so that * * SCNRM2 := sqrt( conjg( x' )*x ) * * * * -- This version written on 25-October-1982. * Modified on 14-October-1993 to inline the call to CLASSQ. * Sven Hammarling, Nag Ltd. * * * .. Parameters .. REAL ONE , ZERO PARAMETER ( ONE = 1.0E+0, ZERO = 0.0E+0 ) * .. Local Scalars .. INTEGER IX REAL NORM, SCALE, SSQ, TEMP * .. Intrinsic Functions .. INTRINSIC ABS, AIMAG, REAL, SQRT * .. * .. Executable Statements .. IF( N.LT.1 .OR. INCX.LT.1 )THEN NORM = ZERO ELSE SCALE = ZERO SSQ = ONE * The following loop is equivalent to this call to the LAPACK * auxiliary routine: * CALL CLASSQ( N, X, INCX, SCALE, SSQ ) * DO 10, IX = 1, 1 + ( N - 1 )*INCX, INCX IF( REAL( X( IX ) ).NE.ZERO )THEN TEMP = ABS( REAL( X( IX ) ) ) IF( SCALE.LT.TEMP )THEN SSQ = ONE + SSQ*( SCALE/TEMP )**2 SCALE = TEMP ELSE SSQ = SSQ + ( TEMP/SCALE )**2 END IF END IF IF( AIMAG( X( IX ) ).NE.ZERO )THEN TEMP = ABS( AIMAG( X( IX ) ) ) IF( SCALE.LT.TEMP )THEN SSQ = ONE + SSQ*( SCALE/TEMP )**2 SCALE = TEMP ELSE SSQ = SSQ + ( TEMP/SCALE )**2 END IF END IF 10 CONTINUE NORM = SCALE * SQRT( SSQ ) END IF * SCNRM2 = NORM RETURN * * End of SCNRM2. * END