緊急！菜鳥求助：怎麽用VB求 壹元三次方程的解 看到網上的代碼，不知道怎麽設置控件 求幫忙控件設置和源代

到我的空間裏面看看，有這方面的做法：QQ412495313

在VB中建立text1，text2，text3，text4和text5五個文本框和command1命令按鈕。text1，text2，text3，text4為對應的a、b、c、d系數輸入框，text5為方程解的輸出框，command1按鈕為操作按鈕（先輸入系數再計算）。在代碼窗口中輸入以下代碼：

Private?Function?cubic(ByVal?a?As?Double,?ByVal?b?As?Double,?ByVal?c?As?Double,?ByVal?d?As?Double)?As?String

Dim?x1r?As?Double,?x1i?As?Double,?x2r?As?Double,?x2i?As?Double,?x3r?As?Double,?x3i?As?Double

Dim?ret?As?String

Dim?J1?As?String,?J2?As?String,?J3?As?String,?J?As?String

hh?=?Chr(13)?+?Chr(10)

ret?=?CubicEquation(a,?b,?c,?d,?x1r,?x1i,?x2r,?x2i,?x3r,?x3i)

If?x1i?=?0?Then

J1?=?"X1="?&?Format$(x1r,?"#0.0###############")?&?";"?+?hh

End?If

If?x1i?>?0?Then

J1?=?"X1="?&?Format$(x1r,?"#0.0###############")?&?"?+?"?&?Format$(x1i,?"#0.0###############")?&?"?i"?&?";"?+?hh

End?If

If?x1i?<?0?Then

J1?=?"X1="?&?Format$(x1r,?"#0.0###############")?&?Format$(x1i,?"#0.0###############")?&?"?i"?&?";"?+?hh

End?If

If?x2i?=?0?Then

J2?=?"X2="?&?Format$(x2r,?"#0.0###############")?&?";"?+?hh

End?If

If?x2i?>?0?Then

J2?=?"X2="?&?Format$(x2r,?"#0.0###############")?&?"?+?"?&?Format$(x2i,?"#0.0###############")?&?"?i"?&?";"?+?hh

End?If

If?x2i?<?0?Then

J2?=?"X2="?&?Format$(x2r,?"#0.0###############")?&?Format$(x2i,?"#0.0###############")?&?"?i"?&?";"?+?hh

End?If

If?x3i?=?0?Then

J3?=?"X3="?&?Format$(x3r,?"#0.0###############")?&?";"?+?hh

End?If

If?x3i?>?0?Then

J3?=?"X3="?&?Format$(x3r,?"#0.0###############")?&?"?+?"?&?Format$(x3i,?"#0.0###############")?&?"?i"?&?";"?+?hh

End?If

If?x3i?<?0?Then

J3?=?"X3="?&?Format$(x3r,?"#0.0###############")?&?Format$(x3i,?"#0.0###############")?&?"?i"?&?";"?+?hh

End?If

J?=?J1?+?J2?+?J3

cubic?=?J

End?Function

Private?Function?CubicEquation?_

(ByVal?a?As?Double,?ByVal?b?As?Double,?ByVal?c?As?Double,?ByVal?d?As?Double,?_

x1r?As?Double,?x1i?As?Double,?x2r?As?Double,?x2i?As?Double,?x3r?As?Double,?x3i?As?Double)?As?String

Dim?e?As?Double,?f?As?Double,?g?As?Double,?h?As?Double,?delta?As?Double

Dim?r?As?Double,?sita?As?Double,?pi?As?Double,?rr?As?Double,?ri?As?Double

If?a?=?0?Then

CubicEquation?=?"Not?a?cubic?equation:?a?=?0"

Exit?Function

End?If

'pi?=?3.14159265358979

pi?=?4?*?Atn(1)

b?=?b?/?a'simplify?to?a=1:?x^3+bx^2+cx+d=0

c?=?c?/?a

d?=?d?/?a

e?=?-b?^?2?/?3?+?c?'substitute?x=y-b/3:?y^3+ey+f=0

f?=?(2?*?b?^?2?-?9?*?c)?*?b?/?27?+?d

If?e?=?0?And?f?=?0?Then

x1r?=?-b?/?3

x2r?=?x1r

x3r?=?x1r

CubicEquation?=?"3?same?real?roots:"

ElseIf?e?=?0?Then?'need?to?deal?with?e?=?0,?or?it?will?cause?z?=?0?later.

r?=?-f'y^3+f=0,?y^3=-f

r?=?Cur(r)

x1r?=?r?-?b?/?3'a?real?root

If?r?>?0?Then?'r?never?=?0?since?g=f/2,?f?never?=?0?there

sita?=?2?*?pi?/?3

x2r?=?r?*?Cos(sita)?-?b?/?3

x2i?=?r?*?Sin(sita)

Else

sita?=?pi?/?3

x2r?=?-r?*?Cos(sita)?-?b?/?3

x2i?=?-r?*?Sin(sita)

End?If

x3r?=?x2r

x3i?=?-x2i

CubicEquation?=?"1?real?root?and?2?image?roots:"

Else?'substitute?y=z-e/3/z:?(z^3)^2+fz^3-(e/3)^3=0,?z^3=-g+sqr(delta)

g?=?f?/?2'-q-sqr(delta)?is?ignored

h?=?e?/?3

delta?=?g?^?2?+?h?^?3

If?delta?<?0?Then

r?=?Sqr(g?^?2?-?delta)

sita?=?Argument(-g,?Sqr(-delta))'z^3=r(con(sita)+isin(sita))

r?=?Cur(r)

rr?=?r?-?h?/?r

sita?=?sita?/?3?'z1=r(cos(sita)+isin(sita))

x1r?=?rr?*?Cos(sita)?-?b?/?3?'y1=(r-h/r)cos(sita)+i(r+h/r)sin(sita),?x1=y1-b/3

sita?=?sita?+?2?*?pi?/?3'no?image?part?since?r+h/r?=?0

x2r?=?rr?*?Cos(sita)?-?b?/?3

sita?=?sita?+?2?*?pi?/?3

x3r?=?rr?*?Cos(sita)?-?b?/?3

CubicEquation?=?"3?real?roots:"

Else'delta?>=?0

r?=?-g?+?Sqr(delta)

r?=?Cur(r)

rr?=?r?-?h?/?r

ri?=?r?+?h?/?r

If?ri?=?0?Then

CubicEquation?=?"3?real?roots:"

Else

CubicEquation?=?"1?real?root?and?2?image?roots:"

End?If

x1r?=?rr?-?b?/?3?'a?real?root

If?r?>?0?Then'r?never?=?0?since?g=f/2,?f?never?=?0?there

sita?=?2?*?pi?/?3

x2r?=?rr?*?Cos(sita)?-?b?/?3

x2i?=?ri?*?Sin(sita)

Else'r?<?0

sita?=?pi?/?3

x2r?=?-rr?*?Cos(sita)?-?b?/?3

x2i?=?-ri?*?Sin(sita)

End?If

x3r?=?x2r

x3i?=?-x2i

End?If

End?If

End?Function

Private?Function?Cur(v?As?Double)?As?Double

If?v?<?0?Then

Cur?=?-(-v)?^?(1?/?3)

Else

Cur?=?v?^?(1?/?3)

End?If

End?Function

Private?Function?Argument(a?As?Double,?b?As?Double)?As?Double

Dim?sita?As?Double,?pi?As?Double

'pi?=?3.14159265358979

pi?=?4?*?Atn(1)

If?a?=?0?Then

If?b?>=?0?Then

Argument?=?pi?/?2

Else

Argument?=?-pi?/?2

End?If

Else

sita?=?Atn(Abs(b?/?a))

If?a?>?0?Then

If?b?>=?0?Then

Argument?=?sita

Else

Argument?=?-sita

End?If

ElseIf?a?<?0?Then

If?b?>=?0?Then

Argument?=?pi?-?sita

Else

Argument?=?pi?+?sita

End?If

End?If

End?If

End?Function

Private?Sub?Command1_Click()

Dim?a?As?Double,?b?As?Double,?c?As?Double,?d?As?Double

Dim?J?As?String,?J1?As?String,?J2?As?String,?P?As?Double

Dim?xr?As?Double,?xi?As?Double

hh?=?Chr(13)?+?Chr(10)

a?=?Val(Text1.Text)

b?=?Val(Text2.Text)

c?=?Val(Text3.Text)

d?=?Val(Text4.Text)

If?a?<>?0?Then

Text5.Text?=?cubic(a,?b,?c,?d)

End?If

If?a?=?0?And?b?<>?0?Then

P?=?c?^?2?-?4?*?b?*?d

xr?=?-c?/?(2?*?b)

Select?Case?P

Case?Is?=?0

x?=?xr

J?=?"X="?&?Format$(x,?"#0.0###############")

Text5.Text?=?J

Case?Is?>?0

xi?=?Sqr(Abs(P))?/?(2?*?b)

J1?=?xr?+?Sqr(Abs(P))?/?(2?*?b)

J2?=?xr?-?Sqr(Abs(P))?/?(2?*?b)

J?=?"X1="?&?Format$(J1,?"#0.0###############")?&?hh?&?"X2="?&?Format$(J2,?"#0.0###############")

Text5.Text?=?J

Case?Is?<?0

xi?=?Sqr(Abs(P))?/?(2?*?b)

J1?=?"X1="?&?Format$(xr,?"#0.0###############")?&?"+"?&?Format$(xi,?"#0.0###############")?&?"i;"?+?hh

J2?=?"X2="?&?Format$(xr,?"#0.0###############")?&?"-"?&?Format$(xi,?"#0.0###############")?&?"i;"

J?=?J1?+?J2

Text5.Text?=?J

End?Select

End?If

If?a?=?0?And?b?=?0?And?c?<>?0?Then

x?=?d?/?c

J?=?"X="?&?Format$(x,?"#0.0###############")

Text5.Text?=?J

End?If

If?a?=?0?And?b?=?0?And?c?=?0?Then

MsgBox?"方程無意義，請重新輸入！",?,?"溫馨提示"

End?If

End?Sub

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