plotting limitted range still going though all data

[<pl...@pi...>]

Hi,

I am calling a simple function max() to detect the two largest peaks in 
the data.


#function to do sample/hold
max(x,y)=(ymax<y) ? ( xmax=x, ymax=y) :ymax ;

# dummy plot to scan data for biggest peak
set term unknown
plot ymax=xmax=0,  datafile using 1:( max(($1),($2)) );
pk0=xmax; ymax=xmax=0;
plot  [pk0+100:]  datafile using 1:( max(($1),($2)) );
pk1=xmax;
set term ''

if (debugging) print "xmax = ",xmax,"; ymax  ",ymax; pause mouse


It's hitting the first one both times.

Now unless I'm getting sleepy, this seems to show that the second call 
to plot with a specified limited range is still going through the 
motions. and evaluating the using clause for all data points in the 
file. Thus all the mechanics are still being gone through only to have 
null output created.

Is this :

?
a) correctly what's happening
b) necessary
c) desirable.

?

If I have a huge data file (that I do sometimes.) it would seem 
advantageous if setting a range pre-empted the rest of plot activity 
until the range condition is true.

Best regards. Peter.