Python 将参数传递给 fsolve
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Passing arguments to fsolve
提问by Ricevind
I'm solving a nonlinear equation with many constants.
I created a function for solving like:
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：
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
Then I want to do:
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)
But fsolveis unpacking dataand passing too many arguments to terminalVfunction, so I get:
但是fsolve正在解包data并将太多参数传递给terminalV函数，所以我得到：
TypeError: terminalV() takes exactly 2 arguments (6 given)
类型错误：terminalV() 正好需要 2 个参数（给出 6 个）
So, my question can I somehow pass a tuple to the function called by fsolve()?
所以，我的问题可以以某种方式将元组传递给调用的函数fsolve()吗？
采纳答案by askewchan
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:
问题是您需要使用星号来告诉您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：
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)
Without fsolve, i.e., if you just want to call terminalVon its own, for example if you want to see its value at Vt0, then you must unpack datawith a star:
没有fsolve，即，如果您只想terminalV自己调用，例如，如果您想查看它在 处的值Vt0，那么您必须data用星号解包：
data = (1800, 994.6, 0.208e-3, 8.931e-4, 9.80665)
Vt0 = 1
terminalV(Vt0, *data)
Or pass the values individually:
或者单独传递值：
terminalV(Vt0, 1800, 994.6, 0.208e-3, 8.931e-4, 9.80665)
回答by pv.
Like so:
Vt = fsolve(terminalV, Vt0, args=[data])
像这样：
Vt = fsolve(terminalV, Vt0, args=[data])
