TIP: A good starting point to bookmark to investigate or review new/replacement API methods for mdlRMatrix and mdlTMatrix functions is the MicroStationAPI.chm help topic: "Linear Transformations: RotMatrix, Transform, DMatrix4d, DMap4d". This parent topic provides quick links to the respective geometry structs and by clicking the far top right link for each page ("List of all public members") you will see a nice concise signature list to review potential candidate replacement methods.
HTH,
Bob