public class Slasq2
- extends java.lang.Object
Following is the description from the original
Fortran source. For each array argument, the Java
version will include an integer offset parameter, so
the arguments may not match the description exactly.
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* SLASQ2 computes all the eigenvalues of the symmetric positive
* definite tridiagonal matrix associated with the qd array Z to high
* relative accuracy are computed to high relative accuracy, in the
* absence of denormalization, underflow and overflow.
* To see the relation of Z to the tridiagonal matrix, let L be a
* unit lower bidiagonal matrix with subdiagonals Z(2,4,6,,..) and
* let U be an upper bidiagonal matrix with 1's above and diagonal
* Z(1,3,5,,..). The tridiagonal is L*U or, if you prefer, the
* symmetric tridiagonal to which it is similar.
* Note : SLASQ2 defines a logical variable, IEEE, which is true
* on machines which follow ieee-754 floating-point standard in their
* handling of infinities and NaNs, and false otherwise. This variable
* is passed to SLASQ3.
* N (input) INTEGER
* The number of rows and columns in the matrix. N >= 0.
* Z (workspace) REAL array, dimension ( 4*N )
* On entry Z holds the qd array. On exit, entries 1 to N hold
* the eigenvalues in decreasing order, Z( 2*N+1 ) holds the
* trace, and Z( 2*N+2 ) holds the sum of the eigenvalues. If
* N > 2, then Z( 2*N+3 ) holds the iteration count, Z( 2*N+4 )
* holds NDIVS/NIN^2, and Z( 2*N+5 ) holds the percentage of
* shifts that failed.
* INFO (output) INTEGER
* = 0: successful exit
* < 0: if the i-th argument is a scalar and had an illegal
* value, then INFO = -i, if the i-th argument is an
* array and the j-entry had an illegal value, then
* INFO = -(i*100+j)
* > 0: the algorithm failed
* = 1, a split was marked by a positive value in E
* = 2, current block of Z not diagonalized after 30*N
* iterations (in inner while loop)
* = 3, termination criterion of outer while loop not met
* (program created more than N unreduced blocks)
* Further Details
* Local Variables: I0:N0 defines a current unreduced segment of Z.
* The shifts are accumulated in SIGMA. Iteration count is in ITER.
* Ping-pong is controlled by PP (alternates between 0 and 1).
* .. Parameters ..
|Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
public static void slasq2(int n,