make local variables local

.. to not interfere with variables in the scripts that source these utils.

math.sh

@@ -8,6 +8,11 @@ SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
 # https://unix.stackexchange.com/questions/89712/how-to-convert-floating-point-number-to-integer
 # xargs: https://stackoverflow.com/questions/19148370/piping-seq-to-printf-for-number-formatting
 divideint () {
+    if [ -z $3 ]; then
+        local scale=2
+    else
+        local scale=$3
+    fi
     bc <<< "scale=$scale; $1/$2" | xargs printf "%.0f\n"
 }
 
@@ -17,25 +22,25 @@ multiint () {
 
 divide () {
     if [ -z $3 ]; then
-        scale=2
+        local scale=2
     else
-        scale=$3
+        local scale=$3
     fi
     bc <<< "scale=$scale; $1/$2"
 }
 
 multiply () {
     if [ -z $3 ]; then
-        scale=2
+        local scale=2
     else
-        scale=$3
+        local scale=$3
     fi
     bc <<< "scale=$scale; $1*$2"
 }
 
 avgoftwo () {
-    sum=$(bc <<< "$1+$2")
-    divideint $sum 2
+    local sum=$(bc <<< "$1+$2")
+    divide $sum 2
 }
 
 max () {