Celsius to Fahrenheit and vice versa in zsh

.zshrc

# usage
# $ deg 10c # Celsius to Fahrenheit
# 50.0
#
# $ deg 115f # Fahrenheit to Celsius
# 46
deg() {
  unit=${1:(-1)}
  d=${1:0:(-1)}
  if [ $unit = c ]
  then
    echo "scale=0; ($d * 1.8) + 32" | bc -l
  else
    echo "scale=0; ($d - 32) / 1.8" | bc -l
  fi
}