

1cROUTINE 
1cDESCRIPTION 


XYaupd 
Top level subroutine that implements the IRAM. 
XYeupd 
This routine computes eigenvectors and/or Schur vectors 

for the computed eigenvalues. 
XYaup2 
Intermediate level interface called by XYaupd that 

performs the iteration. 
Xgetv0 
Initial vector generation subroutine. 
XYaitr 
Arnoldi factorization subroutine. 
Xneigh 
Compute Ritz values and error bounds subroutine for the 

nonsymmetric and nonHermitian eigenvalue problems. 
[s,d]seigt 
Compute Ritz values and error bounds subroutine for 

the symmetric eigenvalue problem. 
XYgets 
Sort the Ritz values and corresponding error
bounds. 
[s,d]Yconv 
Determines which Ritz values satisfy the convergence 

criterion. 
XYapps 
Application of implicit shifts routine. 
Xortc 
Sorting routines for complex vectors. 
[s,d]ortr 
Sorting routine for real vectors. 
[s,d]laqrb 
Compute the eigenvalues and the last components of the 

Schur vectors of an upper Hessenberg matrix. 
[s,d]stqrb 
Compute the eigenvalues and the last components of the 

eigenvectors of a symmetric tridiagonal matrix. 