REAL FUNCTION SSXT1( IJOB, D1, N1, D2, N2, ABSTOL, \$ ULP, UNFL ) * * -- LAPACK test routine (version 3.1) -- * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. * November 2006 * * .. Scalar Arguments .. INTEGER IJOB, N1, N2 REAL ABSTOL, ULP, UNFL * .. * .. Array Arguments .. REAL D1( * ), D2( * ) * .. * * Purpose * ======= * * SSXT1 computes the difference between a set of eigenvalues. * The result is returned as the function value. * * IJOB = 1: Computes max { min | D1(i)-D2(j) | } * i j * * IJOB = 2: Computes max { min | D1(i)-D2(j) | / * i j * ( ABSTOL + |D1(i)|*ULP ) } * * Arguments * ========= * * ITYPE (input) INTEGER * Specifies the type of tests to be performed. (See above.) * * D1 (input) REAL array, dimension (N1) * The first array. D1 should be in increasing order, i.e., * D1(j) <= D1(j+1). * * N1 (input) INTEGER * The length of D1. * * D2 (input) REAL array, dimension (N2) * The second array. D2 should be in increasing order, i.e., * D2(j) <= D2(j+1). * * N2 (input) INTEGER * The length of D2. * * ABSTOL (input) REAL * The absolute tolerance, used as a measure of the error. * * ULP (input) REAL * Machine precision. * * UNFL (input) REAL * The smallest positive number whose reciprocal does not * overflow. * * ===================================================================== * * .. Parameters .. REAL ZERO PARAMETER ( ZERO = 0.0E0 ) * .. * .. Local Scalars .. INTEGER I, J REAL TEMP1, TEMP2 * .. * .. Intrinsic Functions .. INTRINSIC ABS, MAX, MIN * .. * .. Executable Statements .. * TEMP1 = ZERO * J = 1 DO 20 I = 1, N1 10 CONTINUE IF( D2( J ).LT.D1( I ) .AND. J.LT.N2 ) THEN J = J + 1 GO TO 10 END IF IF( J.EQ.1 ) THEN TEMP2 = ABS( D2( J )-D1( I ) ) IF( IJOB.EQ.2 ) \$ TEMP2 = TEMP2 / MAX( UNFL, ABSTOL+ULP*ABS( D1( I ) ) ) ELSE TEMP2 = MIN( ABS( D2( J )-D1( I ) ), \$ ABS( D1( I )-D2( J-1 ) ) ) IF( IJOB.EQ.2 ) \$ TEMP2 = TEMP2 / MAX( UNFL, ABSTOL+ULP*ABS( D1( I ) ) ) END IF TEMP1 = MAX( TEMP1, TEMP2 ) 20 CONTINUE * SSXT1 = TEMP1 RETURN * * End of SSXT1 * END