#
# Illustrate uses of plotting with a watchpoint set
#
#
if (!strstrt(GPVAL_COMPILE_OPTIONS, "+WATCHPOINTS")) {
    print "This copy of gnuplot does not support watchpoints"
    exit  # return to caller
}

# watchpoints are only active on plots "with lines" or "with linespoints"
#
set style data lines

set key left Left reverse title "   "
set border lw 1.2
set tics nomirror
set y2tics 0.25
set link y2

set title "Find threshold values on a derived curve"
plot 'moli3.dat' using 0:(abs($2)*sin($0/6.)**2) smooth cnormal lt -1 lw 2 \
     watch y=.25 watch y=.50 watch y=.75 \
     title "plot FOO smooth cnormal\n watch y=.25 watch y=.50 watch y=.75"
set obj 1 rect from real(WATCH_1[1]), imag(WATCH_1[1]) to graph 2, graph -2
set obj 1 fs empty bo lc "red"
set obj 2 rect from real(WATCH_2[1]), imag(WATCH_2[1]) to graph 2, graph -2
set obj 2 fs empty bo lc "blue"
set obj 3 rect from real(WATCH_3[1]), imag(WATCH_3[1]) to graph 2, graph -2
set obj 3 fs empty bo lc "forest-green"


replot

show watchpoints


Click here for minimal script to generate this plot

set title "Same plot with auto-generated watchpoint hit labels"
set style watchpoint label boxed
set style textbox opaque margin 0,0 lw 0.5
replot


Click here for minimal script to generate this plot

set title "Find and mark intersection of two curves"
set key right reverse Left
unset link y2
set style watchpoint nolabel
set grid
set xrange [50:500]

plot 'silver.dat' using 1:($2 - ($0+$3)) watch y=0.0 lt nodraw
INTERSECT_X = WATCH_1[1]
plot 'silver.dat' using 1:2, '' using 1:($0+$3) watch x=INTERSECT_X
INTERSECT_Y = imag(WATCH_1[1])
show var INTERSECT


set label 1 at INTERSECT_X, INTERSECT_Y point pt 6 ps 3
set arrow 1 from INTERSECT_X, 0.1*INTERSECT_Y to INTERSECT_X, 0.8*INTERSECT_Y noborder
plot 'silver.dat' using 1:2 lw 2, '' using 1:($0+$3) lw 2, \
     keyentry with point pt 6 lc "black" \
     title sprintf("Intersection at  [%.1f, %.1f]", INTERSECT_X, INTERSECT_Y)


Click here for minimal script to generate this plot

unset key
set title "Find y intercepts of a parametric function" offset 0,-1
set xrange [-0.1 : 0.9]
set yrange [ 0.0 : 0.85]
set border 0
set xzeroaxis
set yzeroaxis
set xtics axis
set ytics axis
set sample 250

plot sample [t=-1:3.95] '+' using (FresnelC(t)) : (FresnelS(t)) with lines watch x=0.5 lt 3

show watchpoints


set title "Intercept labels constructed from WATCH_1 array values" noenhanced
set for [i=1:|WATCH_1|] label i at real(WATCH_1[i]), imag(WATCH_1[i])
set for [i=1:|WATCH_1|] label i point pt 7 ps 0.5
set for [i=1:|WATCH_1|] label i sprintf("Hit %d at y = %.4f",i,imag(WATCH_1[i]))
replot



Click here for minimal script to generate this plot