'<Main>
'Option Explicit no longer needed as it is default for FB0.17f and later..
	'+------------------------------------------------------------------------------------------+
	'|    Header:  Evaluation of parameters                                                     |
	'|             DisplayCheck:|Il1 are Alt-0124, Big i, small L, One  ���᎙��=������ܱ�     |
	Const Author="QuadEqus.Bas �2009 by ytwinky, MD"'                                           |
	'|             (ShortCut: none)                                                             |
	'|             THIS IS THE ONLY GOTO IN THE WHOLE PROGRAM..                                 |
	'|    Purpose: Solve quadratic equations(general form)                                      |
	'+------------------------------------------------------------------------------------------+
Type Real As Double
Type QuaEquRec
  As Real x1, x2
  As Integer SqrErr
End Type
Declare Function qegf(a As Real=1, b As Real, c As Real=0) As QuaEquRec

Dim x As QuaEquRec
Print Author
Print "1.:Solve the equation 2x^2+4x-48=0"
x=qegf(2, 4, -48)
Print "x1=" &x.x1 &" x2=" &x.x2 &" SqrErr=" &x.SqrErr
Print "Now check 2*" &x.x1 &"^2+4*" &x.x1 &"-48=0, Result:" &(2*x.x1^2+4*x.x1-48)
Print "And also  2*" &x.x2 &"^2+4*" &x.x2 &"-48=0, Result:" &(2*x.x2^2+4*x.x2-48)
Print "2.:Solve the equation x^2+2x-24=0"
x=qegf(, 2, -24)
Print "x1=" &x.x1 &" x2=" &x.x2 &" SqrErr=" &x.SqrErr &!"\n" _
      &"Now check " &x.x1 &"^2+2*" &x.x1 &"-24=0, Result:" &(x.x1^2+2*x.x1-24) _
      &!"\nAnd also  " &x.x2 &"^2+2*" &x.x2 &"-24=0, Result:" &(x.x2^2+2*x.x2-24) _
      &!"\nExplanation of SqrErr:\nSqrErr=0 ==> no Error\nSqrErr=27 ==> a=0, but a must be<>0" _
      &!"\nSqrErr=-1 ==> radicand<0, but radicand must not be<0"
GetKey
End

Function qegf(a As Real=1, b As Real, c As Real=0) As QuaEquRec
  Dim Result As QuaEquRec
  Dim As Real p, q, d
  If a=0 Then
    Result.SqrErr=27
  Else
    p=b/a
    q=c/a
    d=p*p/4-q
    If d<0 Then
      Result.SqrErr=-1
    Else
      Result.x1=-p*0.5+Sqr(d)
      Result.x2=-p*0.5-Sqr(d)
      Result.SqrErr=0
    End If
  End If
  Return Result
End Function