Hi, thank you for your reply, unfortunately when I've tried the same commands in my version of Maple (Maple 10) it doesn't work and comes up with INTERFACE_PLOT(`...`), INTERFACE_PLOT(`...`), I even opened the maple file you gave and tried the identical commands for the functions you created but they didn't work. Maybe it is to do with the difference in versions. Any ideas? Thanks again

Hi, thank you for your reply, unfortunately when I've tried the same commands in my version of Maple (Maple 10) it doesn't work and comes up with INTERFACE_PLOT(`...`), INTERFACE_PLOT(`...`), I even opened the maple file you gave and tried the identical commands for the functions you created but they didn't work. Maybe it is to do with the difference in versions. Any ideas? Thanks again