REM --- Approximate Euclidean Distance Subroutine
REM --- inputs: V - X coordinate of point 2
REM --- W - Y coordinate of point 2
REM --- X - X coordinate of point 1
REM --- Y - Y coordinate of point 2
REM --- uses: U - temporary Y distance
REM --- output: Z - distance to (V,W) from (X,Y)
200 LET Z=X-V
IF Z<0 THEN LET Z=-Z
LET U=Y-W
IF U<0 THEN LET U=-U
IF Z>=U THEN LET Z=Z+U/2
IF Z