Outside Function Calls: SCIFCT

	Adding new functions to AnalytiCalc can now be done without
modifying them. This will permit you to add practically any functions
desired to AnalytiCalc, provided:
	1. They must be Fortran callable, and
	2. Their arguments must be real*8 or Integer*4, and
	3. They must make minimal (preferably no) use of data
		passed to them in Commons.

Numerous functions in scientific and math libraries satisfy this.
The [.STAT] subdirectory here supplies a few hundred examples which
can be selected from.

	To implement these functions, you need to select what you
want called, and add calls to the functions into the SCIFCT.FOR file
here. This file contains 3 examples, one internal and two in the
Scientific Subroutine Package (SSP.FOR). The external ones are
documented in their source files and were selected because they
do multiple linear regression and chi-squared calculations.
	The comments in SCIFCT.FOR will guide you in adding the
calls. You have to add the function name, some flags for which
arguments are integer, which real, which dummy scratch areas,
and which are output arrays.
	To call a function in this file, if the function name is
abcdef, your call in an AnalytiCalc formula is of the form

*U STabcdef in1;in2;in3;in4;...inN>out1;out2;...;outN

where inN is either a single cell or a range of cells. The caller
is expected to know what the function requires. The SCIFCT
file will ensure that enough arguments are present, and will
convert the arguments to integer or float to match what the
function (abcdef in this case) expects. The method is that
arguments are copied from the spreadsheet into a scratch array
whose dimension is a parameter in SCIFCT. Then the Fortran
function is called with its argument list pointing to the
appropriate place in the scratch array. On return, output
arguments from the called routine are copied into the outN
areas specified in the call in the spreadsheet. Therefore
these may differ from the inputs.
	If scratch areas are needed, they are created on the
fly and need only one cell in the call, PROVIDED their
length is in an argument that appears earlier in the
argument list. If you specify a bigger area than calculated
this way for scratch arguments, it is used. A bit of extra slop
space is added, too, to help avoid problems in this case.
	Output arguments are positional and start with the
first OUTPUT argument of the subroutine. Null output arguments
may be specified by just two semicolons adjacent, so that
  B3:D5;;H2
would specify the rectangular area whose diagonal ends are
B3 and D5, a null argument, then the cell H2.  If the argument
between these is not an output argument, though, anything can
safely be entered here; data is copied only to output arguments.

	It's up to you to document whatever you add, of course.
There are enough subroutines presented here and available from
other places to THOROUGHLY intimidate anyone who isn't a PhD level
mathematician, and with a little work (I trust I've made it minimal)
you can add literally hundreds of strange & wonderful functions to
AnalytiCalc, to be available at your fingertips.  If anyone does
this for a bunch of these routines, I'd appreciate a copy (on tape
please); I won't hold my breath.
	More to the point, if you have a calculation that you do a lot
and want it added, you need not bother with changing it around to fit
it into AnalytiCalc; just tack it in here. Just replace the file
SCIFCT.FTN in the build files with SCIFCT.FOR and link with any
extra objects you pull in. (You can just recompile SCIFCT.FOR and
put it into PCCX.OLB if you like, avoiding a total recompile too.)
The functions added may do other things like plotting, database
queries, communications, open the garage door, etc.  This facility
can also be used to debug algorithms if you like; use the spreadsheet
to enter data and build it with debug, so you can see what your
subroutine is doing without having to write a lot of special
driver routines.
	The subroutine name and the name in the *U STmmmmmm call
do NOT have to be alike, and one *U STmmmmmm call can be used
to call several subroutines if you want. Several of the routines
in the Scientific Subroutine package are set up to be used this
way.
	Enjoy.

	Glenn Everhart
	25 Sleigh Ride Rd.
	Glen Mills, PA 19342