ortho


Purpose

Build MAC or orthogonality from mode shapes and mass (or stiffness) matrix.

Syntax

O[,SF] = ORTHO(shape1[,shape2][,mass][,ctrace][,fname][,'noscale'])

Description

The ORTHOcommand will either calculate a Modal Assurance Criteria (MAC) or orthogonality matrix between a set of mode shapes, depending on the inputs supplied. The resulting matrix will be scaled between 0 and 100.

SHAPE1 and SHAPE2 are imat_shp objects containing the shape(s) to compare. If only one imat_shp is supplied, ORTHO will assume that you want to compare SHAPE1to itself. If the imat_ctrace object CTRACE is supplied, the DOF supplied in CTRACE will be extracted from the shapes for the calculations.

MASS is an optional double matrix. If MASSis supplied, then ORTHO will compute orthogonality. Otherwise, it will compute a MAC. MASSshould be m x m, where m corresponds to the number of DOF in SHAPE1 and SHAPE2. If CTRACEis supplied, then m should be the length of CTRACE, and the order of the DOF in CTRACE should match the order in MASS.

If FNAME is supplied, the resulting orthogonality or MAC matrix will be written to a tab-separated ASCII file. If FNAMEcontains either a '*' or a '?', a file dialog will appear using FNAME as a filter, allowing you to graphically choose the file to write to. This file will contain mode frequencies in the first column and row and the orthogonality or MAC matrix.

SF is an optional output argument. It is a 2x1 cell array containing the scale factors used to normalize the mode shapes if orthogonality was computed and you did not supply the 'noscale' argument. Each cell contains a 1x n numeric vector of scale factors, where n is the number of modes.

Care should be taken to ensure that the mass (or stiffness) matrix DOF and the shape coefficients are in the same coordinate system(s) and units. Any discrepancies will result in an incorrect orthogonality matrix.

Examples

>> Ott=ortho(st, TAM.mass,TAM.aset)
>> Ott=ortho(st,st,TAM.mass,TAM.aset)
>> Otg=ortho(st,sg,TAM.mass,TAM.aset)
>> MACtt=ortho(st,st,ct)
>> MACCtt=ortho(st)

See Also

backexp, modesort