martlab中怎样求积分

lanxuzhang

<>各位老大</P>
<>        在martlab软件中用什么函数可以求积分，望知情者指条明道</P>

daike1983kk

你还是用Mathmiatics 吧。。。。。。

宝宝

<>你是说matlab吧</P><>用diff函数 </P><>DIFF Difference and approximate derivative.
    DIFF(X), for a vector X, is [X(2)-X(1)  X(3)-X(2) ... X(n)-X(n-1)].
    DIFF(X), for a matrix X, is the matrix of row differences,
       [X(2:n, - X(1:n-1,].
    DIFF(X), for an N-D array X, is the difference along the first
       non-singleton dimension of X.
    DIFF(X,N) is the N-th order difference along the first non-singleton
       dimension (denote it by DIM). If N &gt;= size(X,DIM), DIFF takes
       successive differences along the next non-singleton dimension.
    DIFF(X,N,DIM) is the Nth difference function along dimension DIM.
       If N &gt;= size(X,DIM), DIFF returns an empty array.

    Examples:
       h = .001; x = 0:h:pi;
       diff(sin(x.^2))/h is an approximation to 2*cos(x.^2).*x
       diff((1:10).^2) is 3:2:19

       If X = [3 7 5
               0 9 2]
       then diff(X,1,1) is [-3 2 -3], diff(X,1,2) is [4 -2
                                                      9 -7],
       diff(X,2,2) is the 2nd order difference along the dimension 2, and
       diff(X,3,2) is the empty matrix.

    See also GRADIENT, SUM, PROD.</P><P> Overloaded methods
    help sym/diff.m
    help char/diff.m
    help fints/diff.m
    help localtruncps/diff.m
    help localpspline/diff.m
    help localpoly/diff.m
</P>

bob475000

<>int 进入后用help即可学会</P><>查书上符号积分部分也有</P><>diff是求微分</P>

beck

用INT

zijingdijiu

int怎么用啊？

宝宝

<>-- help for sym/int.m ---</P><> INT    Integrate.
    INT(S) is the indefinite integral of S with respect to its symbolic
      variable as defined by FINDSYM. S is a SYM (matrix or scalar).
      If S is a constant, the integral is with respect to 'x'.
    INT(S,v) is the indefinite integral of S with respect to v. v is a
      scalar SYM.
    INT(S,a,b) is the definite integral of S with respect to its
      symbolic variable from a to b. a and b are each double or
      symbolic scalars.
    INT(S,v,a,b) is the definite integral of S with respect to v
      from a to b.

    Examples:
      syms x x1 alpha u t;
      A = [cos(x*t),sin(x*t);-sin(x*t),cos(x*t)];
      int(1/(1+x^2))           returns     atan(x)
      int(sin(alpha*u),alpha)  returns     -cos(alpha*u)/u
      int(besselj(1,x),x)      returns     -besselj(0,x)
      int(x1*log(1+x1),0,1)    returns      1/4
      int(4*x*t,x,2,sin(t))    returns      2*sin(t)^2*t-8*t
      int([exp(t),exp(alpha*t)])  returns  [exp(t), 1/alpha*exp(alpha*t)]
      int(A,t)                 returns      [sin(x*t)/x, -cos(x*t)/x]
                                            [cos(x*t)/x,  sin(x*t)/x]</P><> There is more than one int available.  See also
    help char/int.m
</P>

womiga

<>用int是求符号积分</P>

haotongxue

<>哥们，你也太夸张了，今天还不知MATLAB 怎么求积分</P>

海岩秋沙

<>是不定积分还是数值积分啊?</P><>可以看看在线帮助!!!</P>