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

Code:

**QUADEQ**
a+b*i*
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"