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Re: Try this [message #12948 is a reply to message #12945]

Wed, 23 September 1998 00:00

steinhh
Messages: 260
Registered: June 1994

Senior Member

In article <MPG.1071fa8a1e63e2a49896c8@news.frii.com>
davidf@dfanning.com (David Fanning) writes:
>
> Ray Sterner (sterner@tesla.jhuapl.edu) writes:
>
>> Try this:
>>
>> x=dindgen(1000)/999.*20.
>> for f=0.,10.,.02 do begin plot,/xstyl,x+f*1D6,sin(x) & empty & endfor
>
> Totally cool! :-)

Weird yes, but definitively not cool for those who *want* to plot
those data points!

It took me a while to see what was going on here, but
after running Ray's lines, do:

plot,(x+1D7)(0:200),/xstyle,/ystyle,psym=3

Now, a DOUBLE should have more dynamic range than to say that
e.g., (x+1D7)(50) is *equal* to (x+1D7)(51). Luckily, it does:

IDL> print,(x+1d7)([50,51]),form='(g20)'
10000001.00100100
10000001.02102102

However, it appears that the PLOT command internally just works
with FLOAT precision:

IDL> print,FLOAT((x+1d7)([50,51])),form='(g20)'
1.000000e+07
1.000000e+07

This could have been OK if some "zero point" value (typically the
value of one of the tickmarks) had been subtracted in the process of
converting to float. As it stands, this will have to be done
by the user/programmer.

Regards,

Stein Vidar
(OK, so the visual effect *was* kind of cool :-)

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[Message index]

		Re: Try this By: Karl Krieger on Wed, 23 September 1998 00:00
		Re: Try this By: Joe[2] on Wed, 23 September 1998 00:00
		Re: Try this By: steinhh on Wed, 23 September 1998 00:00
		Re: Try this By: davidf on Tue, 22 September 1998 00:00

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