IIUG Software Repository Files

Subject: square root
From: johnl@informix.com (Jonathan Leffler)
Newsgroups: comp.databases.informix
Date: 9 Oct 1996 10:03:20 -0400

For SQRT, you could use the i4gl_sqrt() function and the underlying
decsqrt() function in the attached shell archive.  Note that this
code uses DECIMAL types throughout and is therefore accurate up to
32 digits.

For general trig, you could consider using the functions in the SELECT
statement:

SELECT SIN(3.1415) FROM SysTables WHERE Tabid = 1;

but (a) that is a ludicrously slow way to do it, and (b) it almost
certainly uses the C math library functions, rather than any more precise
DECIMAL code, so the accuracy will not exceed about 14 digits.  You can get
those functions to exececute more quickly by using simple interface
functions like i4gl_sin():

#include <math.h>
#include <fglsys.h>

int i4gl_sin(int n)
{
	double	x;

	if (n != 1)
		fgl_fatal("i4gl_sin()", 1, -1318);
	popdub(&x);
	retdub(sin(x));
	return(1);
}

If you are using an old version of I4GL, you may not have fglsys.h to declare
the functions like popdub() and retdub() -- it is then simplest to omit the
#include <fglsys.h> line.

Yours,
Jonathan Leffler (johnl@informix.com) #include <disclaimer.h>

>Does anyone know how to compute square root on 4GL?  Also how to compute
>logarithmic and trig functions?