I tried building it with VisualAge 3.08 and os2tk45
Complex.h was missing, I got it from the Visualage includes, along with iostream.h. complexm.lib was missing, I edited it out of the makefile. Almost compiled, I don't know ibmcpp well enough, error was,
...
Object Modules [.obj]: /base:0x10000 /pmtype:pm +
Object Modules [.obj]: "fractz.OBJ"
Run File [fractz.*]: "FRACTZ.EXE"
Map File [FRACTZ.map]: ""
Libraries [.lib]:
Definitions File [nul.def]: "fractz.def"
ILink : fatal error LNK1082: lnkods50.exe : stub file not found
NMAKE : fatal error U1077: 'W:\OS2\CMD.EXE' : return code '12'
Stop.
complex.h seems to be a bunch of math stuff in a class.