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Thread: [TI-83] Solve Quadratic Equations

  1. #1

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    Arrow [TI-83] Solve Quadratic Equations

    Simple program for the Texas Instruments TI-83 graphics calculator, for solving quadratic equations.

    Code:
    QUADEQ
    
    a+bi
    Disp "INSERT A,B,C"
    Prompt A,B,C
    (-B+(√(Bē-4AC)))/(2A)->V
    (-B-(√(Bē-4AC)))/(2A)->W
    If (Bē-4AC)<0
    Then
    Fix 6
    Else
    Float
    End
    Disp "ZEROS:"
    If Str0="Y"
    Then
    Disp V>Frac,W>Frac
    Else
    Disp V>Dec,W>Dec
    End
    ((-B)/(2A))->D
    ADē+BD+C->E
    If A<0
    Then
    Disp "LOCAL MAX="
    Else
    Disp "LOCAL MIN="
    End
    If Str0="Y"
    Then
    Disp E>Frac,"WHEN X=",D>Frac
    Else
    Disp E>Dec,"WHEN X=",D>Dec
    End
    Float
    And an accompanying function to turn fractions mode on and off:
    Code:
    SETMODE
    
    Menu("FRACTIONS?","ON",A,"OFF",B)
    Lbl A
    "Y"->Str0
    Disp "FRACTIONS ON"
    Stop
    Lbl B
    "N"->Str0
    Disp "FRACTIONS OFF"

  2. #2

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    Arrow Re: [TI-83] Solve Quadratic Equations


  3. #3
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    Re: [TI-83] Solve Quadratic Equations

    When I try to run the program, I'm getting this error message:
    ERR: UNDEFINED
    and when I choose Goto, it takes me back to this line:
    If Str0="Y"

    I don't understand what I've done wrong.

  4. #4

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    Re: [TI-83] Solve Quadratic Equations

    I'm sorry, I didn't make it clear in the original post. You need to run the SETMODE program first in order to assign Str0; then run QUADEQ.

    One probably ought to build in a check for this condition in QUADEQ. Perhaps an exercise for you?

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