Calculates the Modal Assurance Criterion (MAC) and the Shape Difference Indicator (SDI) between M#s with matching DOFs in two Data Blocks. The results are saved as two shapes in a Shape Table.
MAC is a measure of the co-linearity of two M#s. Two M#s are co-linear if their values"lie on the same straight line".
This command calculates the MAC between the values of each M# in one Data Block with values of each M# with matching DOFs in a second Data Block.
MAC has values between 0 & 1
If MAC = 1, the values of an M# in one Data Block are co-linear with the values of the M# with matching DOF in another Data Block
If MAC < 1, the values of an M# in one Data Block are not co-linear the values of the M# with matching DOF in another Data Block
SDI is a measure of the difference between two shapes.
This command calculates the SDI between the values of each M# in one Data Block with values of each M# with matching DOFs in a second Data Block.
SDI has values between 0 & 1
If SDI = 1, values of an M# in one Data Block are the same as with the values of the M# with matching DOF in another Data Block
If SDI < 1, values of an M# in one Data Block are not the same as the values of the M# with matching DOF in another Data Block
A good way to examine the MAC & SDI values that were saved in a Shape Table is to use the Display | Magnitude Ranking command in the Shape Table
Execute Display | Magnitude Ranking
Select Shape #1 to display MAC magnitudes as shown below
MAC Magnitude Ranking.
Select Shape #2 to display SDI magnitudes as shown below
SDI Magnitude Ranking.