using bc and a few other things

[cwl157]

How do i use the bc command to do a few floating point calculations. I need it to find the scale for the x and y axis for a graph i have to make. Here is what i have so far the bc part is at the very bottom. The subtraction part works, however, when i try to divide i get a "syntax error line 1, teletype" is the error i get. Can someone tell me how to subtract the max from the min and then divide by 80 and then store it in the variable xScale? Thanks

#!/usr/bin/bash

touch Xpoints
touch Ypoints
varX=0;
while [ "$varX" != "" ]
do
  echo "Enter an X value or a blank space to end input: "
  read varX;
  if [ "$varX" == "" ]
  then
  break;
  else
  xValues[i]=$varX;
  echo $varX >> Xpoints
  fi
  echo "Enter a Y value: "
  read varY;
  yValues[i]=$varY;
  echo $varY >> Ypoints
  (( i++ ))
done

size=${#xValues[*]}
echo $size

i=0

#while [ "$i" < "$size" ]
#do
#echo ${xValues[$i]}
#(( i++ ))
#done

#sort to find maxX, minX, maxY, minY
minX=`sort -g Xpoints | head -1`
echo $minX
maxX=`sort -g Xpoints | tail -1`
echo $maxX
minY=`sort -g Ypoints | head -1`
echo $minY
maxY=`sort -g Ypoints | tail -1`
echo $maxY
#!/usr/bin/bash

touch Xpoints
touch Ypoints
varX=0;
while [ "$varX" != "" ]
do
  echo "Enter an X value or a blank space to end input: "
  read varX;
  if [ "$varX" == "" ]
  then
  break;
  else
  xValues[i]=$varX;
  echo $varX >> Xpoints
  fi
  echo "Enter a Y value: "
  read varY;
  yValues[i]=$varY;
  echo $varY >> Ypoints
  (( i++ ))
done

size=${#xValues[*]}
echo $size

i=0

#while [ "$i" < "$size" ]
#do
#echo ${xValues[$i]}
#(( i++ ))
#done

#sort to find maxX, minX, maxY, minY
minX=`sort -g Xpoints | head -1`
echo $minX
maxX=`sort -g Xpoints | tail -1`
echo $maxX
minY=`sort -g Ypoints | head -1`
echo $minY
maxY=`sort -g Ypoints | tail -1`
echo $maxY

nbrCol=80
#find the original scale
#xScale=`echo "scale=5 ; $maxX - $minX" | bc`
xScale=`echo "scale=5 ; $maxX - $minX" | bc`
echo $xScale
xScale=`echo "scale=5 ; xScale//80" | bc`
echo $xScale

[cwl157]

well i figured out how to use bc to get that value. Now onto the other things part of the subject. I have to be able to store the values in arrays as they are read in. I want to do this with array[i] but i can not figure out how to get it to store it at the next i every time. Anyone know the syntax for this? Here is the part of the code i am looking at now:

varX=0;
while [ "$varX" != "" ]
do
  echo "Enter an X value or a blank space to end input: "
  read varX;
  if [ "$varX" == "" ]
  then
  break;
  else
  xValues[i]=$varX;
  echo $varX >> Xpoints
  fi
  echo "Enter a Y value: "
  read varY;
  yValues[i]=$varY;
  echo $varY >> Ypoints
  (( i++ ))
done

I need to store the y values in yValues variable and store the x values in the xValues variable at index i. Anyone know how to do this? Thanks

*** EDIT ***
Nevermind i got it. It just took some looking