将参数传递给 fsolve [英] Passing arguments to fsolve

问题描述

我正在求解具有许多常数的非线性方程.
我创建了一个用于解决类似问题的函数:

I'm solving a nonlinear equation with many constants.
I created a function for solving like:

def terminalV(Vt, data):
    from numpy import sqrt
    ro_p, ro, D_p, mi, g = (i for i in data)
    y = sqrt((4*g*(ro_p - ro)*D_p)/(3*C_d(Re(data, Vt))*ro)) - Vt
    return y

然后我想做:

data = (1800, 994.6, 0.208e-3, 8.931e-4, 9.80665)
Vt0 = 1
Vt = fsolve(terminalV, Vt0, args=data)

但是 fsolve 正在解包 data 并向 terminalV 函数传递太多参数，所以我得到:

But fsolve is unpacking data and passing too many arguments to terminalV function, so I get:

TypeError: terminalV() 只需要 2 个参数(给定 6 个)

TypeError: terminalV() takes exactly 2 arguments (6 given)

那么，我的问题可以以某种方式将元组传递给 fsolve() 调用的函数吗?

So, my question can I somehow pass a tuple to the function called by fsolve()?

推荐答案

问题是你需要使用星号来告诉你的函数重新打包元组.将参数作为元组传递的标准方法如下:

The problem is that you need to use an asterisk to tell your function to repack the tuple. The standard way to pass arguments as a tuple is the following:

from numpy import sqrt   # leave this outside the function
from scipy.optimize import fsolve

#  here it is     V
def terminalV(Vt, *data):
    ro_p, ro, D_p, mi, g = data   # automatic unpacking, no need for the 'i for i'
    return sqrt((4*g*(ro_p - ro)*D_p)/(3*C_d(Re(data, Vt))*ro)) - Vt

data = (1800, 994.6, 0.208e-3, 8.931e-4, 9.80665)
Vt0 = 1
Vt = fsolve(terminalV, Vt0, args=data)

没有fsolve，即如果你只想自己调用terminalV，例如如果你想在Vt0处看到它的值>，那么你必须用星号解压data:

Without fsolve, i.e., if you just want to call terminalV on its own, for example if you want to see its value at Vt0, then you must unpack data with a star:

data = (1800, 994.6, 0.208e-3, 8.931e-4, 9.80665)
Vt0 = 1
terminalV(Vt0, *data)

或者单独传递值:

terminalV(Vt0, 1800, 994.6, 0.208e-3, 8.931e-4, 9.80665)

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