Prehistoric BC Bug - (nf)

[Robert Herndon]

#N:umn-cs:1300001:000:745
umn-cs!herndon    Jan 31 17:59:00 1984



  There is a bug in the BC library.  The arc-tangent function ("a")
returns pi/4 for the arctangent of any non-zero number.  The cause
of this is a mis-associated "if" statement in the function definition.
The fix for this is to change the definition of the a() function.

The file currently reads:

125a126,128
> 	if(x==1)
> 		if(scale<52)
> return(.7853981633974483096156608458198757210492923498437764/1)

The following may be substituted:

126,130d125
> 	if(x==1) {
> 		if(scale<52) {
> return(.7853981633974483096156608458198757210492923498437764/1)
> 		}
> 	}

Or the lines may be deleted entirely.  This will slow down the
evaluation of a(1) substantially but will not otherwise harm the
function.

				Robert Herndon
				umn-cs!herndon