# 99bottles.gp:
#   Gnuplot is a well-known, portable command-line driven interactive data and 
#   function plotting utility (http://www.gnuplot.info). So arguably it should 
#   have some graphics output. Here is a script for gnuplot version 4.2 that 
#   outputs the 99-bottles-of-beer-song and also draws some bottles on the 
#   screen... (written by Bastian Maerkisch)

# Define a maximum number of bottles in case we do not want so many beers...
if (!exists("max")) max = 99

# Create and initialize the (remaining) bottles counter
if (!exists("bottles")) bottles = max

# Initialize the plot settings
if (bottles == max) \
   unset border;\
   unset tics ;\
   set lmargin 1;\
   set rmargin 1;\
   unset key; \
   set parametric; \
   set xrange [-1:29.5]; \
   set yrange [-11:29]; \
   set samples 561; \
   set style line 1 linetype 1 lc rgb "#008800" lw 0; \
   set style line 2 linetype 1 lc rgb "brown" lw 3; \
   set style line 3 linetype 1 lc rgb "#008800" lw 5;

# Define a string valued function to create the "bottle(s)" string
# Note that there is no name conflict with the bottles variable.
bottles(b) = " bottle" . "s"[0:(b != 1)] . " "

# Function which returns the number b or the string "no more" iff b=0.
# The case of the first letter can be switched by the parameter c
# (c==1 means capital, c==0 lower case)
number(b, c) = (b > 0) ? sprintf("%d", b) : "nN"[c+1:c+1] . "o more"

# We use a ternary operator to decide what to do next -- Get more beer! ;-)
action(b) = (b != 0) ? \
    "Take one down and pass it around" : \
    "Go to the store and buy some more"

# Calculate the number of bottles after "taking one down"
bmm(b) = (b + max) % (max + 1)

# Function to return a complete verse
verse(b) = number(b, 1) . bottles(b) . "of beer on the wall, " . \
           number(b, 0) . bottles(b) . "of beer.\n" .\
           action(b) . ", " .\
           number(bmm(b), 0) . bottles(b - 1) .\
           "of beer on the wall."

# Parametric function definition of one half of a bottle
halfabottle_x(t) = (t < 1) ?  t : ((t<4) ? 1 :