在matlab中求導(dǎo)要進(jìn)行符號(hào)運(yùn)算。

>>syms x;

>>y = x^cos(x);

>>ydot = diff(y, x, 1);%對(duì)x求一階導(dǎo)數(shù)

ydot = ? x^(cos(x) - 1)*cos(x) - x^cos(x)*log(x)*sin(x)??

>> y2dot = diff(y, x, 2)%求二階導(dǎo)數(shù)，求n階導(dǎo)數(shù)同理。??

y2dot = ? cos(x)*(x^(cos(x) - 2)*(cos(x) - 1) - x^(cos(x) - 1)*log(x)*sin(x)) - x^(cos(x) - 1)*sin(x) - log(x)*sin(x)*(x^(cos(x) - 1)*cos(x) - x^cos(x)*log(x)*sin(x)) - x^cos(x)*cos(x)*log(x) - (x^cos(x)*sin(x))/x ?

>> subs(ydot, x, pi)%將x = pi帶入ydot

ans =

? -0.101321183642338

?

轉(zhuǎn)載于:https://www.cnblogs.com/jiangkejie/p/5929657.html

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