matlab编程

E304731541

d=sym(3*x^3-2*x+1);
diff(d,2)
ezplot('cos(x)',[0,pi])//4.2
ezplot('(cos(t))^3','(sin(t))^3',[0,2*pi])//4.3
( o, \! D# v' H' L7 p. {8 vezplot('exp(x)+sin(x*y)',[-2,0.5,0,2])//4.4
1 W4 K* B( v( @8 L7 y1 y! A fminbnd('x+3*(x^2+cos(x))',-1,1)  //直接求
f=sym('x+3*(x^2+cos(x))');//由导数为零来求解
  ff=solve(diff(f));
' T' d8 F' l/ C" c1 R8 M5 Isubs(f,x,ff),subs(f,x,-1),subs(f,x,-1)
( l8 i. d% I5 \% O- osyms x;
int(1/sin(x)^2*cos(x)^2)
syms x z;
1 C- Y$ B' `9 u5 E& `int(x/(1+z^2),x)
4 _8 k! U9 A8 h: K* M0 |4 EA=[1,2,3;4,5,6;7,8,9;10,11,12]
3 J4 n$ x! o  j3 a' |A =
     1     2     3
/ u. n* R0 R6 o5 O     4     5     6
, _! c4 m: N% F, W! @3 _: J     7     8     9
    10    11    12
B=[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
# H/ |+ [+ X6 O% r7 d* |rref(A)
+ ~4 |8 E" Z5 C% F( p9 s# Vx=linspace(0,2*pi,30);
- q4 m9 q0 k4 ?! g0 N* My=sin(x);
1 Z) U1 O! @) mz=cos(x);
plot(x,y,'r',x,z,'pg')
x=linspace(0,2*pi,30);
" b+ F  ?% U& F% Py=sin(x);
z=cos(x);
xlabel('自变量x')
ylabel('函数y')
! |4 z) \, K) dtitle('示意图')
plot(x,y,'r',x,z,'pg'),grid on;
x=linspace(0,2*pi,30);
y=sin(x);
+ q0 e/ T4 c# H0 l: ^: Kz=cos(x);
4 i, r  ?) g; [7 w- {( gplot(x,z,'pg');
+ D0 R6 _9 H* M+ r# G$ E$ |hold on;
! g% B$ p( M. ~plot(x,y,'r')
# _2 w3 u" j7 L5 q+ o/ |" Hx=linspace(0,2*pi,100);
y=sin(x);
, m! R4 h# n: n& l8 Xz=cos(x);
plot(x,y);
title('sin(x)')
pause;
figure(2);
plot(x,z,'pg');
title('cos(x)')
  g3 k3 Y7 I/ {# i* O& Ox=linspace(0,2*pi,30);
y=sin(x);
plot(x,y,'r');
zoom on
p=[1 -4 9 -10];
: W3 N- r$ e' |0 zr=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。
& M$ c( [  @! @2 U( Xr=solve('x^3-4*x^2+9*x-10=0')//简单方法
) Q, j" i$ O1 [) h8 t: Z* hr=solve('x^2-a*x-4*b=0','x')
d=solve('p*sin(x)-r','x')
4 q' U. J, ^1 ]" u% l5 Qr=fzero('x-(cos(x))^2',1)//其中必须输入的是方程对应的函数名
[x,y]=solve('x+y=1','x-11*y=5','x','y')

mrx

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qingqing20072

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xxj198712

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zhula

2# mrx
谢谢啊！！

zhula

2# mrx
' o# L- u# G& _太感谢了

zhula

2# mrx
2 a7 s1 I+ ^: q. D. i( Q5 E最近在做有关促销的文章，可以借鉴，３Ｑ

byit

Thanks you~~