... Up: Science Software Applications . ... It has extensions for creating GUI (Tk) and object-oriented ([incr tcl]) applications. Several Tcl-based tools that may be used for astronomical and other scientific applications have been created and are discussed. One example is ptcl , which registers PGPLOT functions as Tcl commands, creating a powerful interactive plotting package. ... Both programs use the same C code, Tcl commands, and [incr tcl] classes; only the GUIs are different. ...