[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: ATAN function with two ARGS
Ben Tupper wrote:
> In comp.lang.idl-pvwave you write:
> >I have bumped into a conflict between the IDL documentation and IDL output.
> >From the IDL (5.2) docs, the optional argument Y is described as follows:
> >An optional argument.
> >If this argument is supplied, ATAN returns the angle whose tangent
> >is equal to Y/X. If both arguments are zero, the result is undefined.
> >So I tried the following...
> >IDL> help, ATAN(0.0,0.0)
> ><Expression> FLOAT = 0.00000
> >Uhoh! Is it me, or is it Monday morning syndrome?
> When I try the above command, I get
> IDL> help,atan(0.0,0.0)
> <Expression> FLOAT = -NaN
> IDL> help,/struct,!version
> ** Structure !VERSION, 5 tags, length=80:
> ARCH STRING 'alpha'
> OS STRING 'OSF'
> OS_FAMILY STRING 'unix'
> RELEASE STRING '5.2'
> BUILD_DATE STRING 'Oct 30 1998'
> William Thompson
The above was sent to me by William Thompson. Below is the version info for
the platform not returning the undefined value.
I've sent notice of this anomaly to RSI.
<Expression> STRUCT = -> !VERSION Array
** Structure !VERSION, 5 tags, length=40:
ARCH STRING 'sparc'
OS STRING 'sunos'
OS_FAMILY STRING 'unix'
RELEASE STRING '5.2'
BUILD_DATE STRING 'Oct 30 1998'
IDL> help, ATAN(0.0, 0.0)
<Expression> FLOAT = 0.00000
Bigelow Laboratory for Ocean Science