fnder是个什么函数？

sherri

fnder是matlab中的函数吗？是什么函数？在哪个工具箱里？

xxf

用help 查一下就查出来了

mulan

splines工具箱里的

coldspring

FNDER Differentiate a function.

    FNDER(F) returns the (representation of the) first derivative of the
    univariate function contained in F (and in the same form).  

    FNDER(F,DORDER) returns the DORDER-th derivative, with DORDER expected
    to be of the form [d1,...,dm] in case the function in F is m-variate,
    and, for each i=1,..,m,  di  an integer to indicate that the function
    in F is to be differentiated di-fold with respect to its i-th argument.
    Here, di may be negative, resulting in di-fold integration with respect
    to the i-th argument.

    FNDER(...) does not work for rational splines; for them, use FNTLR instead.

    FNDER(...) works for functions in stform only in a very limited way, namely
    only for type tp00, and, for that, DORDER can only be [1 0] or [0 1].

    Examples:

       fnval( fnder( sp, 2), 3.14 );
    gives the value at 3.14 of the function in sp, while

       sp0 = fnint( fnder( sp ) );
    gives a function that differs from sp by some constant only (namely, by
    its value at 0).