 LAPACK  3.8.0 LAPACK: Linear Algebra PACKage

## ◆ dsxt1()

 double precision function dsxt1 ( integer IJOB, double precision, dimension( * ) D1, integer N1, double precision, dimension( * ) D2, integer N2, double precision ABSTOL, double precision ULP, double precision UNFL )

DSXT1

Purpose:
``` DSXT1  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 ) }```
Parameters
 [in] IJOB ``` IJOB is INTEGER Specifies the type of tests to be performed. (See above.)``` [in] D1 ``` D1 is DOUBLE PRECISION array, dimension (N1) The first array. D1 should be in increasing order, i.e., D1(j) <= D1(j+1).``` [in] N1 ``` N1 is INTEGER The length of D1.``` [in] D2 ``` D2 is DOUBLE PRECISION array, dimension (N2) The second array. D2 should be in increasing order, i.e., D2(j) <= D2(j+1).``` [in] N2 ``` N2 is INTEGER The length of D2.``` [in] ABSTOL ``` ABSTOL is DOUBLE PRECISION The absolute tolerance, used as a measure of the error.``` [in] ULP ``` ULP is DOUBLE PRECISION Machine precision.``` [in] UNFL ``` UNFL is DOUBLE PRECISION The smallest positive number whose reciprocal does not overflow.```
Date
December 2016

Definition at line 108 of file dsxt1.f.

108 *
109 * -- LAPACK test routine (version 3.7.0) --
110 * -- LAPACK is a software package provided by Univ. of Tennessee, --
111 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
112 * December 2016
113 *
114 * .. Scalar Arguments ..
115  INTEGER ijob, n1, n2
116  DOUBLE PRECISION abstol, ulp, unfl
117 * ..
118 * .. Array Arguments ..
119  DOUBLE PRECISION d1( * ), d2( * )
120 * ..
121 *
122 * =====================================================================
123 *
124 * .. Parameters ..
125  DOUBLE PRECISION zero
126  parameter( zero = 0.0d0 )
127 * ..
128 * .. Local Scalars ..
129  INTEGER i, j
130  DOUBLE PRECISION temp1, temp2
131 * ..
132 * .. Intrinsic Functions ..
133  INTRINSIC abs, max, min
134 * ..
135 * .. Executable Statements ..
136 *
137  temp1 = zero
138 *
139  j = 1
140  DO 20 i = 1, n1
141  10 CONTINUE
142  IF( d2( j ).LT.d1( i ) .AND. j.LT.n2 ) THEN
143  j = j + 1
144  GO TO 10
145  END IF
146  IF( j.EQ.1 ) THEN
147  temp2 = abs( d2( j )-d1( i ) )
148  IF( ijob.EQ.2 )
149  \$ temp2 = temp2 / max( unfl, abstol+ulp*abs( d1( i ) ) )
150  ELSE
151  temp2 = min( abs( d2( j )-d1( i ) ),
152  \$ abs( d1( i )-d2( j-1 ) ) )
153  IF( ijob.EQ.2 )
154  \$ temp2 = temp2 / max( unfl, abstol+ulp*abs( d1( i ) ) )
155  END IF
156  temp1 = max( temp1, temp2 )
157  20 CONTINUE
158 *
159  dsxt1 = temp1
160  RETURN
161 *
162 * End of DSXT1
163 *
double precision function dsxt1(IJOB, D1, N1, D2, N2, ABSTOL, ULP, UNFL)
DSXT1
Definition: dsxt1.f:108