Re: various observations (added to list)

[<br...@ph...>]

Daniel J Sebald wrote:

> 2)  3D plot layout is definitely the thing most in need of work post 
> 4.2.  The default colorbox seems too big and out of place.  The x-y 
> plane position seems slightly limited.  Let me give an example to 
> illustrate a few things.  The following is meant to show a zero mean, 
> unit variance Gaussian r.v. density.  The contour is supposed to 
> represent the variance in some way, and there are supposed to be a set 
> of Gaussian samples with zero mean, unit variance.

> set hidden3d
> set contour
> set isosamples 60
> set view 68, 28, 1, 1
> unset key
> unset title
> set cntrparam levels discrete 0.1
> set style line 1 linecolor rgb "black"
> set term x11 2
> set parametric
> set xrange [-5:5]
> set yrange [-5:5]
> set urange [-5:5]
> set vrange [-5:5]
> set xyplane at -0.2
> splot u,v,( 1/(2*pi) * exp(-0.5 * (u**2 + v**2)) ) with line ls 1, \
>  sqrt(-2*log(rand(0)))*cos(2*pi*rand(0)),sqrt(-2*log(rand(0)))*sin(2*pi*rand(0)),-0.2 
> with points pointtype 7 linecolor rgb "black"
> 
> My intent was to have the points on the x-y plane and drop the x-y plane 
> to leave enough space that the surface plot doesn't obstruct the 
> points.  Using the "set xyplane #" just didn't seem to get me there.  
> The axes would remain the same and the x-y plane would extend off the 
> plot, which just seemed silly.
> 
> Then "set xyplane at -0.2" and setting the z-value of the points to -0.2 
> puts the points and x-y plane in the same plane, but notice that the 
> line of the z-axis still extends down to where the xyplane used to be.  
> (That's a bug, isn't it?  Or am I missing something?)  Consequently, the 
> plot isn't using the space efficiently.
> 
> 3)  It sure is annoying going through the trouble of looking up in 
> "test" (x11) the number of the symbol desired, and then the symbol comes 
> out differently in the output file (png).  

Well, then don't.  As it's said throughout engineering: test what you 
fly, not what is easy to test.  There's no particularly strong reason 
not to optimize the plot directly in PNG format.

> Actually, I'd think that the "linecolor", "pointtype" is an extraneous 
> syntax.  Couldn't it just be "points type 7 color rgb "black""?  

No, because that syntax would fail miserably in the case of 'with 
linespoints': what type does "type" address: that of the points, or that 
of the lines?

> 4)  In a related category would be contours.  I wanted to force the 
> contours to be all of the same color, in this case black.  That doesn't 
> seem possible.

It is.  "help set noclabel"

> 5)  In the example, I really only want about 25 samples.  IS THERE SOME 
> WAY TO CONTROL THIS?  Setting the samples # doesn't seem to effect 
> this.  

You'll have to elaborate.  Exact input, output, and a description why 
the output isn't what you wanted, please.

> 6)  Would anyone object to a patch for a math function "randn()" 
> generating unit variance normal distribution random values using the 
> Box-Mueller method?  

I would: it's not needed.  You have rand(), you have invnorm, that's all 
you need.  Also see 'stat.inc'.

> 7)  Anyone notice that the above example in the x11 terminal is rather 
> slow refresh (even when the sample points are not included)?  I realize 
> that it takes a while to create the rendering of hidden lines with so 
> many iso-lines, but once it is drawn one would think the refresh in 
> gnuplot-x11 would be fairly fresh.  

An why would one think that?  What made you think hidden3d would work 
faster on replots?

> Yes, it has a lot of lines; but still, drawing lines shouldn't be so
> slow.

Drawing them isn't.  Determining those that are not to be drawn is.