10 REM ********************************
   20 REM Newton Raphson Curve Root Finder
   30 REM           By Mark Ray
   40 REM ********************************
   50 REM NC100/200 Version
   60 REM Downloaded from Tim's Amstrad NC Users' Site
   70 REM http://www.ncus.org.uk
   80 REM Originally from the Amstrad Notepad Users' Web
   90 CLS:PRINT 'TAB(20);"Newton Raphson Curve Root Finder"'
  100 INPUT LINE "Function Y="F$:INPUT "First Approximation :"U
  110 N=0:REPEAT:PRINT "Approximation ";N;" = ";U:X=U
  120   U=U-(EVAL(F$)/FNdiff(F$,X)):N=N+1:UNTIL U=X:A=GET:CHAIN"BAG"
  130 DEF FNdiff(F$,VX):LOCAL Y1,Y2,X
  140 X=VX:Y1=EVAL(F$):X=X*1.000001:Y2=EVAL(F$)
  150 =(Y2-Y1)/(X-VX)