WP34s program submission: Quadratic fit

[Andrew Nikitin]

This is an implementation of quadratic fit for WP-34s. If only 3 points are entered, this may be used for quadratic interpolation.
Similar function was implemented in HP30b, if you missed it, here it is.

// (C) 2013 Andrew Nikitin

// Fit quadratic polynomial to empirical data

// program operates in stack size 4

// uses regJ and regK to accumulate [SIGMA]x^3 and [SIGMA]x^4

// uses stat registers to accumulate other sums

// stores coefficients of quadrature fit in regA, regB, regC

// Initialize:

//   XEQ'QF'

// Clears sums, but not coefficients

// Enter point:

//   y ENTER x R/S (or [A])

// Result:

//   number of points entered so far

// Calculate coefficients (needs at least 3 points):

//   [B]

// Result:

//   a=regA=regZ

//   b=regB=regY

//   c=regC=regX

//   (order compatible with SLVQ)

// Evaluate Ax[^2]+Bx+C polynomial:

//   x [C]

// Result:

//   Ax[^2]+Bx+C

  LBL'QF'

    SSIZE4

    CL[SIGMA]

    CLx

    STO J

    STO K

    XEQ 00

    STOP

    XEQ A

    BACK 002

// Accumulate sums, including [SIGMA]x^3 and [SIGMA]x^4

  LBL A

    [SIGMA]+

    RCL L

    ENTER

    x^3

    STO+ J

    *

    STO+ K

  LBL 00

    CLx

    n[SIGMA]

    RTN

// delete point

  LBL 65 // XEQ -

    [SIGMA]-

    RCL L

    ENTER

    x^3

    STO- J

    *

    STO- K

    GTO 00

// Fit quadratic

  LBL B

    LocR 016

    RCL K

    STO .03

    RCL J

    STO .02

    STO .06

    # 002

    n[SIGMA]

    x<=? Y

    ERR 15

    STO .07

    [SIGMA]x

    STO .04

    STO .08

    [SIGMA]x[^2]

    STO .01

    STO .05

    STO .09

    [SIGMA]y

    STO .12

    [SIGMA]xy

    STO .11

    [SIGMA]x[^2]y

    STO .10

    1

    1

    3

    .

    0

    3

    0

    3

    ENTER

    1

    2

    2

    .

    0

    3

    0

    1

    # 125

    LINEQS

    RCL .15

    STO A

    RCL .14

    STO B

    RCL .13

    STO C

    RTN

// Evaluate Ax^2+Bx+C polynomial at regX

  LBL C

    ENTER

    RCL* A

    RCL+ B

    *

    RCL+ C

    RTN

  END

[Marcus von Cube, Germany]

Hi Andrew,

nice submission. :-)

It will find its way into the library if Pauli or I find the time to integrate it.

[Paul Dale]

It is in the library now :)

I've not included it in the standard library in flash.

- Pauli