Question

熟悉mathematica的高手，请问解方程组得不出结果问题。

Wp = 200 Pi;
Ws = 300 Pi;
Rp = 1;
Rs = 16;
NSolve[{x - Wp/Power[10^(Rp/10) - 1, (2*y)^-1] == 0,
x - Ws/Power[10^(Rs/10) - 1, (2*y)^-1] == 0}, {x, y}]

我想要计算x和y，可是总得不出来，是不是有什么问题？

错误显示：
NSolve::nsmet: This system cannot be solved with the methods available to NSolve. >>

out:= NSolve[{-200 (-1 + 10^(1/10))^(-(1/(2 y))) \[Pi] + x ==
0, -300 (-1 + 10 10^(3/5))^(-(1/(2 y))) \[Pi] + x == 0}, {x, y}]

Answer 1

Solve和NSolve都是解代数方程的,对超越方程要用FindRoot并给定初值,此时只能求得数值解.改写如下:
Wp = 200 Pi;
Ws = 300 Pi;
Rp = 1;
Rs = 16;
FindRoot[{x - Wp/Power[10^(Rp/10) - 1, (2*y)^-1] == 0,
x - Ws/Power[10^(Rs/10) - 1, (2*y)^-1] == 0}, {{x, 1}, {y, 1}}]
结果为
{x -> 700.9275972, y -> 6.177981243}

Answer 2

你这方程就不对，自己看下，对同一个y，x等于两个不同的值