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file ortxir.rdm
last revised 21 Jan 97

ortx7a., ortx10a.v2001, scale complex eigenvectors for genralized mass as 
an identity matrix

     Alters are provided for SOLs 107 and 110 to scale the complex
eigenvectors such that they produce a unit generalized mass matrix.  
The SOL 107 alter extends the fluid- structure symmetric option to
complex eigensolutions.  (A symmetric input matrix capability for
fluid-structure problems was introduced in version 69.  This alter
package extends the symmetric formulation to complex eigensolutions). 
The complex eigensolvers in general do not provide orthogonal vectors
for repeated roots.  If you find that there are repeated roots perturb
the model to separate the roots if you want to use this alter package to
produce an uncoupled generalized mass matrix.  The alter package will
provide unit terms on the diagonal of the generalized mass matrix for
all conditions, but for repeated roots the matrix may be coupled. For
SOL 110 it is required that the real eigensolution use MASS
normalization. (This is the default normalization for all real
eigensolution methods.) 

     Test problem ortx72 demonstrates use of the alter on a fluid-
structure model.  Test problem ortx101 includes an alter which confirms 
that the eigenvectors scaled at the modal basis produce unit generalized
mass at the p-set level.  Several other similar test problems 
demonstrate other features.