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VB解方程
解一元一次方程：
專注于為中小企業(yè)提供網(wǎng)站建設(shè)、做網(wǎng)站服務(wù),電腦端+手機(jī)端+微信端的三站合一,更高效的管理,為中小企業(yè)原州免費做網(wǎng)站提供優(yōu)質(zhì)的服務(wù)。我們立足成都，凝聚了一批互聯(lián)網(wǎng)行業(yè)人才，有力地推動了成百上千家企業(yè)的穩(wěn)健成長，幫助中小企業(yè)通過網(wǎng)站建設(shè)實現(xiàn)規(guī)模擴(kuò)充和轉(zhuǎn)變。
設(shè)置4個文本框，分別代表一元一次方程中的參數(shù)k,b,x,y
分別命名txtk,txtb,txtx,txty.計算按鈕命名為cmdCalc。
在代碼窗口里粘貼如下代碼:
Private Sub cmdCalc_Click()
Dim k, b As Long
k = txtk.Text
b = txtb.Text
If txtx.Text = "x" Then
MsgBox "x的值為:" (txty.Text - b) / k
ElseIf txty.Text = "y" Then
MsgBox "y的值為:" k * txtx.Text + b
End If
End Sub
計算時求x則在txtx那里輸入一個x，
求y則在txty那里輸入一個y，
在各文本框中輸入?yún)?shù)，
然后按下按鈕，
就有提示框彈出，顯示結(jié)果。
一元二次方程：
privat sub command1_click()
dim a,b,c,x1,x2,d as sigle
a=val(textl.text)
b=val(text2.text)
c=val(text3.text)
d=b^2-4*a*c
if d0 then
x1=(-b+sqr(d))/(2*a)
x2=(-b-sqr(d))/(2*a)
else if d=0 then
x1=(-b/2*a)
x2=x1
else msgbox"方程沒有實根"
end if
text4.text="x1=" x1 "" "x2=" x2
end sub
sub min(byref a() as integer)
dim i,j as interger
for i=1 to 9
for j=i+1 to 10
if a a(i)a(j) then
t=a(j)
a(i)=a(j)
a(j)=t
end if
next
next
end sub
private sub command_(click)
dim b(1 to 10) as interger
dim a(1 to 10) as interger
randomize
for i=1 to 10
a(i)=int(rnd*90)+10
list1.additem a(i)
b(i)=int(rnd*90)+ 10
list2.additem b(i)
next
call min(a)
call min(b)
if a(1)b(1) then
m=a(1)
else
m=b(1)
end if
text1.text="A,B種的最小值：" vbcrlf m
end sub
一元三次方程：
針對方程"ax^3+bx^2+cx+d=0"的求根程序。
控件只需一個Command1，結(jié)果顯示在“立即”中。
代碼如下。（參考）
========================
Private Sub Command1_Click()
Dim x1r As Double, x1i As Double, x2r As Double, x2i As Double, x3r As Double, x3i As Double
Dim ret As String
Const eq = "ax^3+bx^2+cx+d=0"
a = InputBox("請輸入a", eq)
b = InputBox("請輸入b", eq)
c = InputBox("請輸入c", eq)
d = InputBox("請輸入d", eq)
ret = CubicEquation(a, b, c, d, x1r, x1i, x2r, x2i, x3r, x3i) '5x^3+4x^2+3x-12=0
Debug.Print "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" ret
Debug.Print x1r; " + "; x1i; " i"
Debug.Print x2r; " + "; x2i; " i"
Debug.Print x3r; " + "; x3i; " i"
End Sub
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
'Cubic equation(v2.2), coded by btef (please let this line remain)
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
二元一次方程：
Dim a, b, c As Integer
Dim x, y As Single
Dim d As Double
a = Val(InputBox("輸入二次項系數(shù)"))
b = Val(InputBox("輸入一次項系數(shù)"))
c = Val(InputBox("輸入常數(shù)項"))
d = b ^ 2 - 4 * a * c
If d 0 Then
MsgBox "方程無解"
ElseIf d = 0 Then
x = -b / (2 * a)
MsgBox "方程有一個解：" x
Else
x = (-b + Sqr(d)) / (2 * a)
y = (-b - Sqr(d)) / (2 * a)
MsgBox "方程有兩個解：" x "和" y
End If
三元一次方程：
方程組如下,
ax+by+cz=d
a'x+b'y+c'z=d'
a"x+b"y+c"z=d"
其中x,y,z為未知數(shù),a,a',a",b,b',b",c,c',c",d,d',d",為用戶輸入的數(shù)值
解N元一次方程，indat為N+1行、N列的數(shù)組，outdat為N個元素的數(shù)組
Public Sub 解方程(ByRef InDat() As Double, ByVal InDatCount As Long, ByRef OutDat() As Double, ByRef OutDatCount As Long)
Dim Xt() As Double
Dim Dt As Double
Dim Ss As Long
Dim OtSCount As Long
Dim XtOut() As Double
If InDatCount 1 Then
ReDim Xt(1 To InDatCount - 1, 1 To InDatCount) As Double
For j = 1 To InDatCount - 1 '行
For i = 2 To InDatCount + 1 '列
Xt(j, i - 1) = InDat(j, i) * InDat(InDatCount, 1) / InDat(1, 1) - InDat(InDatCount, i)
Next i
Next j
OtSCount = 0
解方程 Xt, InDatCount - 1, XtOut, OtSCount
Dt = 0
For i = 1 To InDatCount - 1
Dt = Dt + InDat(InDatCount, i + 1) * XtOut(i)
Next i
Dt = Dt + InDat(InDatCount, i + 1)
ReDim Preserve OutDat(1 To 1 + OtSCount) As Double
OutDat(1) = -Dt / InDat(InDatCount, 1)
For i = 2 To OtSCount + 1
OutDat(i) = XtOut(i - 1)
Next i
OutDatCount = 1 + OtSCount
Else
ReDim OutDat(1 To 1) As Double
If InDat(1, 1) 0 Then
OutDat(1) = -InDat(1, 2) / InDat(1, 1)
Else
OutDat(1) = 0
End If
OutDatCount = 1
End If
End Sub
VB.NET 求一元二次方程的程序
(-b+(b^2-4ac))/(2a) (-b+(b^2-4ac))/(2a) 是2個根
Delta = b * b - 4 * a * c '求得b*b-4*a*c并存放在變量Delta中
If Delta = 0 Then '如果Delta的值為0
Re = -b / (2 * a)
b * b - 4 * a * c＝b^2-4ac=0
-b/(2a)是唯一解
VB.net如何輸出代數(shù)式,比如計算帶參數(shù)的一元二次方程,請寫清程序
額，我可以用vb6.0的語句回答您，給您參考，就是不知道您可以轉(zhuǎn)化成.net語句與否。
'添加text1,text2,text3用于記錄a,b,c的值
Private?Sub?Command1_Click()
On?Error?GoTo?check
Dim?a,?b,?c,?result1,?result2
a?=?Text1.Text
b?=?Text2.Text
c?=?Text3.Text
result1?=?(((-1)?*?b)?+?Sqr(b?^?2?-?4?*?a?*?c))?/?2?*?a
result2?=?(((-1)?*?b)?-?Sqr(b?^?2?-?4?*?a?*?c))?/?2?*?a
MsgBox?"x1=?"??result1??"??x2=?"??result2
Exit?Sub
check:
MsgBox?"error!please?check?your?number!"
End?Sub
VB.NET 如何繪制數(shù)學(xué)代數(shù)式（公式、方程、函數(shù)解析式等）？
絕對值是“|”，可以直接顯示，同理對數(shù)可用log(x)代替，根號和其他不支持顯示。
如果要顯示數(shù)學(xué)式子，只能畫吧。
計算時可用“^”求冪或求根，“/”表示除法和分?jǐn)?shù)線，還有math類。
vb.net編寫一元一次方程代碼，如－x＋6＝3
解： 移項得：-X=3-6
合并同類項得：-X=-3
系數(shù)化為1得：X=3
名稱欄目：vb.net解方程 VB解方程
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