I used this code to call CATIA :
C=actxserver('Catia.Application')
C = COM.Catia_Application
and I got this error :
Error using feval Custom interface is not supported on a 64-bit version of MATLAB.
Error in actxserver (line 87) h=feval(['COM.' convertedProgID], 'server', machinename, interface);
Error in firstcall (line 1) C=actxserver('Catia.Application')