; HP 42S RPN Function Plotter
; author Neil Franklin, last modification 2010.09.12


; program stuff
; uses register 01 for loop counter


PRGM

  ; function specific stuff

LBL "SINE"                  ; draw a sine, can replace sine with anything else

  ; basic stuff, any function

  CLLCD                     ; blank space for drawing

  1.131                     ; display X coordinates run this range, 1 to 131
  STO 01                    ;   use as loop counter for ISG
LBL 01                      ;   loop target for GTO after ISG

  RCL 01                    ; get X coordinate
  IP                        ; remove end value, to compute Y coordinate from it

  1                         ; shift to range 0 to 130
  -
  130                       ; scale to range 0 to 1, for interface
  /

  ; function specific stuff

  360                       ; scale input to degrees range 0..360
  x

  SIN                       ; do sine, gives -1 to +1

  1                         ; shift to range 0 to 2
  +
  2                         ; scale to range 0 to 1, for interface
  /

  ; basic stuff, any function

  15                        ; scale to range 0 to 15
  *
  16                        ; shift+mirror to range 16 (bottom) to 1 (top)
  x<>y
  -

  RCL 01                    ; get X coordinate, together with existing Y
  IP                        ; remove end value, to plot X/Y
  PIXEL                     ; and draw it

  ISG 01                    ; standard counted loop stuff
  GTO 01

PRGM

; display stays until <- is pressed to abort