svd_H


Purpose

Calculate singular value shapes from FRF matrix (including mass-weighted).

Syntax

[ods,v] = svd_H(f[,TAM][,freqlim])
ods = svd_H(f)

Description

SVD_H calculates the singular value shapes for an FRF matrix over a specified frequency range. These shapes can then be used by SPATIAL_FILTER to reduce the number DOF used for a modal analysis.

F is a set of FRF. All of the functions in F must have the same OrdNumDataType and OrdDenDataType, and must have consistent abscissas. SVD_H will extract a consistent REFxRES matrix of FRF from the supplied input.

TAM is an optional structure containing the mass matrix. It must have the fields .aset (containing an imat_ctrace of response DOF) and .mass (containing the mass matrix). If not supplied, all of the consistent response DOF will be used, and the mass matrix will be set to the identity matrix.

FREQLIM is an optional 1x2 numeric vector specifying the frequency range to analyze. If not supplied, the full frequency range of the FRF will be used.

ODS is an imat_shp containg the Operational Deflected Shapes, which is the U matrix from the SVD calculation. The frequencies of ODS correspond to the singular vectors S from the SVD calculation.

V is the Force Pattern matrix, which correspond to the right singular vectors of the SVD calculation.

Example

>> [ODS,V] = svd_H(f,[45 50]);
>> g = spatial_filter(f,ODS(1:20),TAM);

See also

imat_fn/truncate, spatial_filter, svd_T