Sgrayplot
=========

smooth 2D plot of a surface using colors



Calling Sequence
~~~~~~~~~~~~~~~~


::

    Sgrayplot(x,y,z,<opt_args>)
    Sgrayplot(x,y,z [,strf, rect, nax, zminmax, colminmax, mesh, colout])




Arguments
~~~~~~~~~

:x,y real row vectors of size n1 and n2.
: :z real matrix of size (n1,n2). `z(i,j)` is the value of the surface
  at the point (x(i),y(j)).
: :<opt_args> This represents a sequence of statements
  `key1=value1,key2=value2`,... where `key1`, `key2,...` can be one of
  the following: strf, rect, nax, zminmax, colminmax, mesh, colout.
: :strf is a string of length 3 `"xyz"` (by default `strf= "081"`)
    :x controls the display of captions.
        :x=0 no caption.
        : :x=1 captions are displayed. They are given by the optional argument
          `leg`.
        :

    : :y controls the computation of the actual coordinate ranges from the
    minimal requested values. Actual ranges can be larger than minimal
    requirements.
        :y=0 no computation, the plot use the previus (or default) scale
        : :y=1 from the rect arg
        : :y=2 from the min/max of the x, y data
        : :y=3 built for an isometric scale from the rect arg
        : :y=4 built for an isometric plot from the min/max of the x, y data
        : :y=5 enlarged for pretty axes from the rect arg
        : :y=6 enlarged for pretty axes from the min/max of the x, y data
        : :y=7 like y=1 but the previus plot(s) are redrawn to use the new
          scale
        : :y=8 like y=2 but the previus plot(s) are redrawn to use the new
          scale
        :

    : :z controls the display of information on the frame around the plot.
    If axes are requested, the number of tics can be specified by the
    `nax` optional argument.
        :z=0 nothing is drawn around the plot.
        : :z=1 axes are drawn, the y=axis is displayed on the left.
        : :z=2 the plot is surrounded by a box without tics.
        : :z=3 axes are drawn, the y=axis is displayed on the right.
        : :z=4 axes are drawn centred in the middle of the frame box, with the
          box disabled.
        : :z=5 axes are drawn centred in the middle of the frame box, with the
          box enabled.
        :

    :

: :rect This argument is used when the second character y of argument
  `strf` is 1, 3 or 5. It is a row vector of size 4 and gives the
  dimension of the frame: `rect=[xmin,ymin,xmax,ymax]`.
: :nax This argument is used when the third character z of argument
  `strf` is 1. It is a row vector with four entries `[nx,Nx,ny,Ny]`
  where `nx` ( `ny`) is the number of subgraduations on the x (y) axis
  and `Nx` ( `Ny`) is the number of graduations on the x (y) axis.
: :zminmax, colminmax, mesh, colout See `fec`_.
:



Description
~~~~~~~~~~~

`Sgrayplot` is the same as `grayplot` but the plot is smoothed. The
function `fec` is used for smoothing. The surface is plotted assuming
that it is linear on a set of triangles built from the grid (here with
n1=5, n2=3):


::

    _____________
    | /| /| /| /|
    |/`_`_|/`_`_|/`_`_|/`_`_| 
    | /| /| /| /| 
    |/`_`_|/`_`_|/`_`_|/`_`_|


The function `colorbar`_ may be used to see the color scale.

The parameter `zminmax` is useful for animation purpose (see an
example after) and the parameter `colminmax` lets the user choose a
part of the current colormap (see the `fec`_ help page).

Enter the command `Sgrayplot()` to see a demo.



Sample
~~~~~~



Examples
~~~~~~~~


::

    // example #1
    x=-10:10; y=-10:10;m =`rand`_(21,21);
    `clf`_()
    `xset`_("colormap",`hotcolormap`_(64))
    Sgrayplot(x,y,m, strf="011", rect=[-20,-20,20,20])
    
    // example #2
    t=-%pi:0.1:%pi; m=`sin`_(t)'*`cos`_(t);
    `clf`_()
    `xset`_("colormap",`jetcolormap`_(64))
    `colorbar`_(-1,1)
    Sgrayplot(t,t,m, strf="041")
    
    // example #3: an animation display cos(t)*sin(x)sin(y).
    n = 30;
    nt = 100;
    x = `linspace`_(0,2*%pi,n);
    y = `linspace`_(0,%pi,n/2);
    z = `sin`_(x')*`sin`_(y);
    t = `linspace`_(0,4*%pi,nt);
    `show_window`_(); `clf`_()
    f=`gcf`_();
    f.color_map=`jetcolormap`_(64);
    f.pixmap='on';
    `colorbar`_(-1,1)
    Sgrayplot(x,y,`cos`_(t(1))*z, strf="042", zminmax=[-1,1])
    c=`gce`_(),e=c.children
    `xtitle`_("Kaa''s eyes")
    for i = 1:nt
      e.data(:,3)=`matrix`_(`cos`_(t(i))*z,-1,1);
      `show_pixmap`_()
    end
    f.pixmap='off';




See Also
~~~~~~~~


+ `fec`_ pseudo-color plot of a function defined on a triangular mesh
+ `fgrayplot`_ 2D plot of a surface defined by a function using colors
+ `grayplot`_ 2D plot of a surface using colors
+ `Sfgrayplot`_ smooth 2D plot of a surface defined by a function
  using colors
+ `colorbar`_ draw a colorbar


.. _colorbar: colorbar.html
.. _grayplot: grayplot.html
.. _Sfgrayplot: Sfgrayplot.html
.. _fgrayplot: fgrayplot.html
.. _fec: fec.html