Coordinate Modal Assurance Criterion (COMAC) is an extension to the MAC calculation that identifies the degrees of freedom that are the source of low correlation between the models. To compute COMAC, the modes in both models need to be paired. In the MAC Calculator context, this can either be accomplished using the Automatic Mode Pairing Algorithm or by pairing modes manually in the MAC Frequency Worksheet.
Once the modes have been paired, COMAC is computed as:
Where the following notation is employed:
COMAC value for degree of freedom (dof) 𝓍.ℳ number of paired modes in both models.
set of File 1 modes shapes at dof 𝓍 for all paired modes.
set of File 2 modes shapes at dof 𝓍 for all paired modes.
complex conjugate of 
, 
.