[英]Numerical solving of overdetermined, nonlinear equation system in Python
这是我的问题的一个最小示例-使用scipy.optimize.leastsq解决
from scipy.optimize import leastsq
from numpy import array, exp, sin, cos
def MatrixFun(x, *par):
a, b, c, d = par
m11 = a*sin(x[0])+b*cos(x[1])
m12 = c*cos(x[0])*sin(x[1])
m21 = c*sin(x[0])/cos(x[1])
m22 = d*exp(x[0]*x[1])
M = array([[m11, m12], [m21, m22]])
return M
def Residualvector(x, parameters):
MatrixAim = MatrixFun([-1 , 1], *parameters)
return (MatrixFun(x, *parameters)-MatrixAim).flatten()
parameters = [1, 2, 3, 4]
start = [0, 0]
print(leastsq(Residualvector, start, args=parameters))
问题:
- 需要一个良好的起点
- 无法在我的实际系统中收敛到所需的值
- 我需要x的约束
这是示例问题的我的蛮力解决方案
from numpy import ones, array, arange, exp, sin, cos, sum, abs, argmin
from itertools import product as iterprod
def MatrixFun(x, *par):
a, b, c, d = par
m11 = a*sin(x[0])+b*cos(x[1])
m12 = c*cos(x[0])*sin(x[1])
m21 = c*sin(x[0])/cos(x[1])
m22 = d*exp(x[0]*x[1])
M = array([[m11, m12], [m21, m22]])
return M
def ResidualMatrix(x, parameters):
MatrixAim = MatrixFun([-1 , 1], *parameters)
return MatrixFun(x, *parameters)-MatrixAim
def MyBruteMatrixMinimizer(ResidualMatrix, ranges, args=()):
pathongrid = list(iterprod(*ranges))
pathlength = len(pathongrid)
MatSum = ones(pathlength)
for i in range(pathlength):
MatSum[i] = sum(abs(ResidualMatrix(pathongrid[i], args)))
pathgoal = pathongrid[argmin(MatSum)]
return pathgoal
parameters = [1, 2, 3, 4]
ranges = [arange(-2,0,1e-2), arange(0,2,1e-2)]
print(MyBruteMatrixMinimizer(ResidualMatrix, ranges, args=parameters))
问题:
- 慢
- 稳定性不清楚
我宁愿使用scipy.optimize.brute或scipy.optimize.basinhopping两者都导致错误TypeError: fsolve: there is a mismatch between the input and output shape of the 'func' argument 'F'
。 这很明显,因为我的矩阵具有比变量更多的方程(超定)。
到目前为止,我唯一的想法是总结尽可能多的方程式的绝对值以减小输出形状的大小-但我对此绝对不满意。
对于替代或改进的解决方案或任何其他建议,我将不胜感激。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.