0.7.0 - time value of money (TVM); multiple BASE word sizes

• 0.7.0 (2023-11-20)
  • STAT
    • fix broken Sigma+ and Sigma- when Y==0
    • use alternate equation for SLOP (slope) which works when the Y
      data points are the same
    • fix "stack lift disable" feature of Sigma+ and Sigma- which
      probably got broken during an earlier refactoring
    • check for division by zero when calculating weighted mean WMN, and
      show 9.9999999999999E99 to indicate error, allowing weightedX (or
      weightedY) to be evaluated even if the other is undefined
  • BASE
    • implement WSIZ (set word size) restricted to 8, 16, 24, and 32
      (inspired by HP-16C and Free42)
    • display appropriate number of digits for various WSIZ values, for
      various base modes (HEX, OCT, BIN)
    • display ellipsis character on left most digit in BIN mode if
      the binary number cannot be fully displayed using 14 digits on the
      screen
    • Breaking Change: change order of BDIV results in X and Y
      registers
      • now X=quotient=Y/X and Y=remainder=Y%X
      • allows easier recovery of original X using LastX *
  • MATH: add LN1+, E^X-
    • implement log(1+x) and e^x-1 respectively
    • more accurate than their naive implementations when x is close to 0
    • use mathematical identities involving hyperbolic sinh() and
      asinh() functions to avoid roundoff errors
  • TVM
    • add TVM (time value of money) submenu hierarchy (inspired by HP-12C
      and HP-30b)
    • implement relatively simple Newton-Secant root solver to calculate
      the I%YR from the other 4 TVM variables
    • significant performance and robustness improvements can probably be
      made in the future
  • add storage register arithmetic operations
    • STO+, STO-, STO*, STO/
    • RCL+, RCL-, RCL*, RCL/
  • convert to multi-page flash application
    • now consumes 2 flash pages (2 x 16 kiB)
  • CLEAR multiple times to clear RPN stack
    • If CLEAR is pressed on an empty edit line (just a _ cursor), then
      the message "CLEAR Again to Clear Stack" will be displayed.
    • If CLEAR is pressed again right after this message, the RPN stack is
      cleared, invoking the ROOT > CLR > CLST menu function.
    • Provides a quick shortcut to the CLST function which can be
      difficult to reach when the current menu item is deeply nested in
      another part of the menu hierarchy.
    • The TI-OS does not support 2ND CLEAR, it returns the same keycode as
      CLEAR. So invoking CLST on multiple CLEAR presses seemed like
      the most reasonable workaround.
  • implement jumpBack for MODE button shortcut
    • When ROOT > MODE is reached through the hierchical menu, the
      ON/EXIT/ESC button goes back up the menu hierarchy to the parent,
      the ROOT.
    • When ROOT > MODE is invoked through the MODE button on the
      keyboard, the ON/EXIT/ESC button jumps back to the previous menu
      location, instead of going back up the menu tree.
    • This allows quick changes to the FIX, SCI, and ENG display
      modes, without losing one's place in the menu hierarchy.
  • fix incorrect handling of DEL after a FIX, SCI, or ENG mode
    • when the DEL (backspace) button is pressed after a 2-digit argument
      of a FIX (or SCI etc), one of the digits of the 2-digit argument
      remained in the input buffer
    • the fix now correctly clears the input buffer when transitioning into
      edit mode from a normal mode
  • Potential Breaking Change: STO, RCL, FIX, SCI, ENG argument
    prompt is no longer saved and restored on QUIT or OFF
    • a new Command Arg parser was required to support storage register
      arithmetics
    • it uses a secondary GetKey() parsing loop which implements its own
      2ND QUIT and 2ND OFF handlers
    • the state of the secondary GetKey() parsing loop is not saved and
      restored

0.6.0 - save and restore app state; add carry flag; add BASE ops from HP-16C

• 0.6.0 (2023-09-22)
  • save application state
    • preserve app state into an appvar named RPN83SAV upon exit
    • reconstruct the app state upon restart
  • save X register to TI-OS ANS only on 2ND QUIT or 2ND OFF
    • previously saved to ANS every time X was changed
    • no user-visible change, but is more efficient internally
  • rename P>R to >REC, and R>P to >POL
    • for consistency with other conversion functions, and for consistency
      with HP-42S
    • I prefer the P>R and R>P but the difference is not worth breaking
      consistency
  • support custom MenuGroup handlers
    • absorb changeMenuGroup() functionality into the dispatchMenuNode()
    • add onExit events into changeMenuGroup()
    • add custom mBaseHandler for BASE menu to activate or deactivate
      the baseNumber upon entering or leaving the BASE menu hierarchy
  • BASE mode
    • make all BASE operations use u32 integers, even DEC mode
    • add Carry Flag which is updated for arithmetic, shifting, rotating
      operations
      • add SCF (set carry flag),CCF (clear carry flag), CF? (get
        carry flag)
      • add C or - display indicator
    • remove base number indicator (DEC, HEX, OCT, BIN) from the
      status line (top line)
      • no longer needed since those menu items show a "dot" when selected
      • the base number is only relevant within the BASE menu hierarchy
    • add ASL (arithmetic shift left), RLC (rotate left through carry
      flag), RRC (rotate right through carry flag)
    • add SLn, SRn, RLn, RRn, RLCn, RRCn (shift or rotate Y
      for X times)
    • add CB (clear bit), SB (set bit), B? (get bit)
    • add REVB (reverse bits), CNTB (count bits)
  • add additional HELP pages
    • CFIT Models
    • BASE Ops

0.5 - statistics and curve fit; menu selector dots

• 0.5.0 (2023-08-31)
  • USER_GUIDE.md, README.md
    • Update "Menu Indicator Arrows" section with latest screenshots which
      changed the menu arrows.
    • rename 'Menu Strip' to 'Menu Row' for consistency with HP-42S
      terminology.
  • BASE
    • display just a bare - for negatives numbers in BASE modes (instead
      of ... which is now reserved for valid numbers which overflows the
      number of digits supported by the display)
    • validate that the X and Y values are in the range of [0, 2^32)
      when performing bitwise operations (e.g. B+, AND, XOR, etc).
      Floating point numbers are truncated to u32 integers before the
      bitwise operations are performed.
  • Add menu selector dots
    • Replicate HP-42S menu selector dots, where a menu item can be both an
      action (e.g. select DEG) and a selection indicator.
    • display modes: FIX, SCI, ENG
    • trig modes: RAD, DEG
    • base modes: DEC, HEX, OCT, BIN
  • Improve menu name centering algorithm.
    • No change for strings which are even-number of pixels wide.
    • Strings which are odd-number of pixels wide are now centered
      perfectly, instead of being off-centered by one-px to the left.
    • Allows strings which are 17px wide to be rendered properly.
  • Add STAT menu items
    • 1 or 2 variable statistics
    • Sigma+ (add data point), Sigma- (remove data point)
    • SUM, MEAN, WMN (weighted mean)
    • SDEV (sample standard deviation), SCOV (sample covariance)
    • PDEV (population standard deviation), PCOV (population covariance)
  • Add CFIT curve fit menu items
    • Y>X (forcast X from Y)
    • X>Y (forcast Y from X)
    • SLOP (least square fit slope)
    • YINT (least square fit y-intercept)
    • CORR (correlation coefficient)
    • LINF (linear curve fit model)
    • LOGF (logarithmic curve fit model)
    • EXPF (exponential curve fit model)
    • PWRF (power curve fit model)
    • BEST (choose best curve fit model)
  • Fix RPN stack lift logic for pending input
    • Simplify stack lift logic to handle empty and non-empty pending input
      consistently.
    • If the input buffer is empty (showing just a _ cursor), then any
      subsequent keystroke that generates a single value (e.g. PI or
      STAT:N) replaces the empty X register.
    • If the input buffer is pending but not empty (i.e. has digits with a
      trailing _ cursor), then subsequent keystrokes causes a stack lift,
      preserving the pending input into the Y register.
    • If the subsequent keystroke is a function that consumes an X
      register, then the empty input buffer is assumed to be a 0 value.
  • Allow data transfer between RPN83P and TI-OS through the ANS variable.
    • When the RPN83P app starts, the TI-OS ANS variable (if Real) is
      available as the LastX register.
    • When the RPN83P app exits, the most recent X register becomes
      avaiable in TI-OS as the ANS variable.
  • Add X Root Y menu item under MATH

0.4 - more BASE function; improve speed of PRIM by 7x

• 0.4.0 (2023-08-16)
  • More BASE menu functions:
    • SL (shift left), SR (shift right), RL(rotate left circular), RR` (rotate right circular).
    • B+, B-, B*, B/
    • BDIV (division with remainder)
  • Map +, -, *, and / buttons to their bitwise counterparts when in
    HEX, OCT, or BIN modes.
    • Too confusing to have floating point operations bound to the
      easy-to-reach buttons while in HEX, OCT or BIN modes.
    • This is consistent with the HP-42S.
  • PRIM (isPrime)
    • change result values:
      • 1 if the number is a prime, or
      • smallest prime factor (always greater than 1) if not prime.
    • preserve the original X, and push it up to Y
      • allows the / button to be chained with additional PRIM to
        calculate all prime factors
      • see Prime Factors for details
    • improve speed by 7X using u32 integer routines instead of floating
      point routines

0.3.3 - use pandoc to convert markdown to PDF files

• 0.3.3 (2023-08-14)
  • Add Makefile targets for converting GitHub markdown files to PDF files.
  • Update some sections in README.md and USER_GUIDE.md.
  • No code change.

0.3.2 - add executive summary in README.md

• 0.3.2 (2023-08-13)
  • Add executive summary of the app at the top of README.md.
  • No code change.

0.3.1 - add animated GIFs of Examples 1 and 2

• 0.3.1 (2023-08-13)
  • Add animated GIF to illustrate Examples 1 and 2 in README.md.
  • No code change.

0.3 - rearrange some menu items for usability

• 0.3 (2023-08-13)
  • Move CLRG from F1 position to F3. Move CLX to F1. If the F1
    is accidentally hit twice when selecting the CLR menu group, then
    invoking CLX is a lot less destructive than invoking CLRG.
  • Move IP,FP,... menu strips before the ABS,SIGN,... menu strip. The
    IP,FP functions seem more frequently used than the ABS,SIGN functions.

Full Changelog: v0.2.1...v0.3

0.2.1 - update README.md, no code change

• 0.2.1 (2023-08-13)
  • Update README.md. Test minor version number with new release.
  • No code change.

Full Changelog: v0.2...v0.2.1

0.2 - update installation instructions to reference GitHub releases

• 0.2 (2023-08-13)
  • Update downloading and installation instructions.