freeware http://groups.yahoo.com/group/mathc/

* Calculus : Piecewise-defined functions.

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Windows : Dev-C++ 4
Linux : gcc abc.c -lm Return
a.out Return

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* You can compile the *.c files directly without create a project.

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c01a_1a.c fa.h : With two functions.
c01a_1b.c fb.h
c01a_1c.c fc.h

c01a_2a.c fa.h : With three functions.
c01a_2b.c fb.h
c01a_2c.c fc.h

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The members can try these links :

http://groups.yahoo.com/group/mathc/files/C/D/c01a.zip