Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!njin!princeton!phoenix!englandr
From: englandr@phoenix.Princeton.EDU (Scott Englander)
Newsgroups: comp.databases
Subject: Passing fields as parameters in FoxBASE
Keywords: FoXBASE dBase parameter
Message-ID: <9478@phoenix.Princeton.EDU>
Date: 18 Jul 89 05:12:40 GMT
Organization: Princeton University, NJ
Lines: 41

I've written a simple function that i'd like to reference in a REPLACE
statement.  I'd like to pass it a field like 

dTdt(tr2)
where tr2 is the field name
Here's the function:

**************
*dTdt.prg  Q compute time derivative  using central difference
*value returned is in units/s
parameter T          && field to operate on
missing = -99.0
twomin = 1.3889e-3   && 2 minutes in days
n = recno()
if n > 1
   go n-1
   t1 = lintime
   Tlast = T
   go n+1
   t2 = lintime
   Tnext = T
   if t2-t1 <twomin   && make sure data are continuous
      return (Tnext - Tlast)/120   && return time derivative over 2 min
   else
      return missing
   end if
else
   return missing
endif
*****************

but as is, the function interprets the parameter to be the current value
of the parameter, and skipping to a new record within the function does
not change that value.

Also, if there is a way to do this, do i have to be careful about
setting the record pointer back to where it was upon entry of the
function in order for a REPLACE ALL to work properly?
-- 

                                               - Scott