matlab编程

E304731541

d=sym(3*x^3-2*x+1);
diff(d,2)
/ O2 }! X% g; _/ _5 @, Vezplot('cos(x)',[0,pi])//4.2
8 w5 I' u$ ^! @  T0 q2 S9 oezplot('(cos(t))^3','(sin(t))^3',[0,2*pi])//4.3
ezplot('exp(x)+sin(x*y)',[-2,0.5,0,2])//4.4
! M* @0 n$ R$ [0 d2 ^# X* l fminbnd('x+3*(x^2+cos(x))',-1,1)  //直接求
/ R/ d  E& R9 {* q0 \. q. m9 a f=sym('x+3*(x^2+cos(x))');//由导数为零来求解
  ff=solve(diff(f));
/ `, @; b$ f8 k5 n* R% {) [# Ksubs(f,x,ff),subs(f,x,-1),subs(f,x,-1)
7 Q& f; P. Q& J2 H4 D! P, lsyms x;
int(1/sin(x)^2*cos(x)^2)
0 N9 B. I* e! t- q8 [7 b$ usyms x z;
- h1 y8 w4 l: P5 Iint(x/(1+z^2),x)
# {0 f3 F- J$ F/ eA=[1,2,3;4,5,6;7,8,9;10,11,12]
( X8 W# v6 H( u( e) e% H& U+ x& z# L0 w2 ~A =
0 ?0 N& H4 r& T     1     2     3
# v/ Y$ `: T8 x# a* a: X5 I     4     5     6
     7     8     9
    10    11    12
* M) c( h/ u: ?! q- m/ `5 gB=[0,1,1;2,2,1;1,1,1];
A*B
A^3//错误，矩阵的幂必须矩阵的行列相同才行
rref(A)
5 W5 s4 E% \8 kx=linspace(0,2*pi,30);
3 B6 |0 t; i5 l% {; ty=sin(x);
z=cos(x);
plot(x,y,'r',x,z,'pg')
x=linspace(0,2*pi,30);
! u9 U$ K3 J: x: e/ F6 Ky=sin(x);
. _% `  f4 l  e; z5 ]! A: gz=cos(x);
xlabel('自变量x')
ylabel('函数y')
, k# E- [4 K1 Z5 [3 U. }+ G! {! Utitle('示意图')
- \! ~7 x" `# S" e2 q& _plot(x,y,'r',x,z,'pg'),grid on;
x=linspace(0,2*pi,30);
" _* s8 f" k! [8 d9 u9 sy=sin(x);
1 P0 _( U4 @4 D7 ?; Nz=cos(x);
plot(x,z,'pg');
. M; C7 Y: k3 _hold on;
plot(x,y,'r')
1 k0 c. m- J4 x( Cx=linspace(0,2*pi,100);
y=sin(x);
* _. V! F+ R7 i, U, z* K% d: n$ W- \z=cos(x);
. C5 n, Q+ o! T& c; P; Y: gplot(x,y);
- y8 Z; `  n. J8 v% R; wtitle('sin(x)')
, ^2 \; U, L4 opause;
figure(2);
7 t- ~) w: U0 {& X7 l# dplot(x,z,'pg');
0 Z! g/ K2 r8 Wtitle('cos(x)')
1 q+ k8 ~7 R+ O$ d2 l& Hx=linspace(0,2*pi,30);
y=sin(x);
plot(x,y,'r');
# n* o( _/ G* S: E/ Izoom on
, G* a+ s: W4 K0 {! P+ V. t7 ^4 ~p=[1 -4 9 -10];
7 e6 R4 M; s+ g3 o7 E7 |r=roots(p)//次数小于等于4，若大于4则用该命令不一定能求出所有根的准确形式。
, z# Y  G- ~; I6 T2 E4 ^/ i0 \r=solve('x^3-4*x^2+9*x-10=0')//简单方法
+ Z2 V1 a) v. V0 ?) R* S  vr=solve('x^2-a*x-4*b=0','x')
% R2 }/ h9 T: qd=solve('p*sin(x)-r','x')
r=fzero('x-(cos(x))^2',1)//其中必须输入的是方程对应的函数名
# M% {/ a/ Y* z[x,y]=solve('x+y=1','x-11*y=5','x','y')

mrx

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qingqing20072

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qingqing20072

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qingqing20072

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xxj198712

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zhula

2# mrx
谢谢啊！！

zhula

2# mrx
太感谢了

zhula

2# mrx
9 {. V8 O6 y% d2 V6 E最近在做有关促销的文章，可以借鉴，３Ｑ

byit

Thanks you~~