Confusion over syntax in a package

Hello,

I am new to R and I am attempting to use the ProbForecastGOP package
for some research I am conducting.

The package works fine when I call the functions from the command line
as the examples instruct.

However, I am attempting to step through some of the functions so that
I can obtain a better idea of what is going on.  I have come to the
following command:

calc.dist(coord1.day.index,coord2.day.index,id.day.index)

I know what this is supposed to do, it is calculating the geographic
distance between a series of latitude and longitude points.  However,
I am informed by R that no such function exists.  I searched through
the whole package for a function declaration, rooted through the R
help and googled for the same and came up with nothing.  Interestingly
there is a second command that also won't function on its own:

calc.difference(gop.res.day)

Same result, I cannot find any listing of a 'calc' function.

The strange thing is that everything works fine when I run the example
commands from the command lines, when the function is called instead
of calling each line individually, it works perfectly.

Can anyone shed light on what 'calc' may be?

Many thanks,
Ryan Glover