Re: [Plplot-general] RGB mapping for plsmap1

[Alan W. I. <ir...@be...>]

On 2004-12-04 22:37-0700 Curtis Cooper wrote:

> I think the PLplot colormap setting functions expect color ranges clamped
> between [0,1].
>
> Cheers,
> Curtis

> On Sat, 4 Dec 2004, Tune Kamae wrote:
>
>> Dear PLplot experts,
>>
>>             z=arange(1.0,1.05,0.05)

                         ^^^

Tune, following up on what Curtis said, any number in the range 0 --> 1
including those end-points is okay.  But the above gives on my platform
the two-point
array

[ 1.    1.05]

which is clearly out of bounds.  Alternatively, for slightly different
floating-point rounding it would only give you [1.] which I don't think you
want.

I think you meant 0.0 for the lower limit which gives on my platform
[ 0.    0.05  0.1   0.15  0.2   0.25  0.3   0.35  0.4   0.45  0.5   0.55  0.6
          0.65  0.7   0.75  0.8   0.85  0.9   0.95  1.  ]

Which should be fine so long as some stray round-off error doesn't change that
1.0 to 1.0+eps or else stick on an extra 1.05 value at the upper limit.

The 1.0 to 0.0 change might make your logic work, but better yet, I would
keep the floating point logic to a minimum, that is, use integer arrays (to
make sure you get the correct number of values exactly), convert them to
floating point by multiplying by 0.05, then redefine the upper end (as you
do already) to make sure.

z = 0.05*arange(21)
z[20]=1.

HTH.

Alan
__________________________
Alan W. Irwin
email: ir...@be...
phone: 250-727-2902

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

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for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
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Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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