Plotsh

#!/bin/bash

# Plotsh 1.0
#
# Arkanon <arkanon@lsd.org.br>
# 2012/12/18 Thu 16:45:01
#
# Output sample: <http://goo.gl/y32hh>

export LC_ALL=C
export   TERM=xterm

resize &> /dev/null
tput civis
oldstty=$(stty -g)
stty -echo -icanon time 0 intr '^-'
clear


  black=0
   blue=1
  green=2
   cyan=3
    red=4
magenta=5
 yellow=6
  white=7


vxradio=10
vyradio=5
     bg=$black
  style="b"


rxradio=$(echo "scale=3;$(tput cols )/2"   | bc)
ryradio=$(echo "scale=3;$(tput lines)/2"   | bc)
xfactor=$(echo "scale=3;$rxradio/$vxradio" | bc)
yfactor=$(echo "scale=3;$ryradio/$vyradio" | bc)


print()
{
  local _c=$1       # column
  local _l=$2       # line
  local _f=$3       # foreground color
  local _b=$4       # background color
  local _s=$5       # style
  local _t=$6       # text
  [ $_l = c ]               && _l=$[ $(tput lines)        /2]
  [ $_c = c ]               && _c=$[($(tput cols )-${#_t})/2]
  [ $_l -lt 0 -o $_l = -0 ] && _l=$[$(tput lines)+$_l-1     ]
  [ $_c -lt 0 -o $_c = -0 ] && _c=$[$(tput cols )+$_c-${#_t}]
  tput setf $_f
  tput setb $_b
  case $_s in
    b) tput bold ;; # bold
    u) tput smul ;; # underlined
    r) tput rev  ;; # reverse
    *) tput dim  ;; # normal
  esac
  tput sc
  tput cup  $_l $_c
  echo -en "$_t"
  tput rc
  tput sgr0
}


round()
{
  # round(a) = sign(a)*(abs(a)+.5)
  #  sign(a) = a/abs(a)
  #   abs(a) = ${a#-}
  [ $1 = 0 ] && echo 0 || echo "($1/${1#-})*(${1#-}+.5)/1" | bc
}


map()
{
  local x=$1
  local y=$2
  local c=$(echo "scale=3; ($vxradio+1*$x)*$xfactor" | bc)
  local l=$(echo "scale=3; ($vyradio-1*$y)*$yfactor" | bc)
  echo "$c $l"
  echo "$(round $c) $(round $l)"
}


plot()
{
  local   fn=$1
  local incr=$2
  local   fg=$3
  local  dot=$4
  for x in $(seq -$vxradio $incr $vxradio)
  do
    y=$(echo "scale=3;"$(echo $fn | sed "s/x/$x/g") | bc -l)
    (( $(bc <<< "$y>-$vyradio") > 0 & $(bc <<< "$y< $vyradio") > 0 )) && print $(map $x $y | tail -n1) $fg $bg $style "$dot"
  done
}


# examples
  plot "s(x)"      .1  $red   "o"
  plot "x^2/2-3"   .05 $blue  "+"
  plot "-1*x/2-.5" .1  $green "."


tput cnorm
stty "$oldstty"


# EOF