runge-kutta

问题 I'm in a project in my University and I have to implement the Runge-Kutta 4-order integrator using Python. I know I can use for example Sympy, but the goal here is implement the method, the code is ready written in Fortran language, so basically I have a data base with the correct values of solutions and I have to get similar solutions in my code. However, we have some problems; I did the same several times using linear equations ( first and second order ), however this is a second order

问题 I'm in a project in my University and I have to implement the Runge-Kutta 4-order integrator using Python. I know I can use for example Sympy, but the goal here is implement the method, the code is ready written in Fortran language, so basically I have a data base with the correct values of solutions and I have to get similar solutions in my code. However, we have some problems; I did the same several times using linear equations ( first and second order ), however this is a second order

问题 Hello I have to program a python function to solve Lorenz differential equations using Runge-Kutta 2cond grade sigma=10, r=28 and b=8/3 with initial conditions (x,y,z)=(0,1,0) this is the code i wrote, but it throws me an error saying overflow encountered in double_scalars , and I don't see what is wrong with the program from pylab import * def runge_4(r0,a,b,n,f1,f2,f3): def f(r,t): x=r[0] y=r[1] z=r[2] fx=f1(x,y,z,t) fy=f2(x,y,z,t) fz=f3(x,y,z,t) return array([fx,fy,fz],float) h=(b-a)/n

问题 Hello I have to program a python function to solve Lorenz differential equations using Runge-Kutta 2cond grade sigma=10, r=28 and b=8/3 with initial conditions (x,y,z)=(0,1,0) this is the code i wrote, but it throws me an error saying overflow encountered in double_scalars , and I don't see what is wrong with the program from pylab import * def runge_4(r0,a,b,n,f1,f2,f3): def f(r,t): x=r[0] y=r[1] z=r[2] fx=f1(x,y,z,t) fy=f2(x,y,z,t) fz=f3(x,y,z,t) return array([fx,fy,fz],float) h=(b-a)/n

来源： https://stackoverflow.com/questions/58810439/is-there-a-better-way-to-simulate-pid-control-in-python-with-scipys-solve-ivp

来源： https://stackoverflow.com/questions/58810439/is-there-a-better-way-to-simulate-pid-control-in-python-with-scipys-solve-ivp

问题 I wrote the code to solve Lorenz equations using RK-4 method in C++. I have to plot the attractor plot and I have some difficulty in solving the 3 first order coupled differential equation using RK-4 method. Here is my code: /* Solving 3 coupled first order differential equations using RK4 for the Lorentz system dxdt = sig*(y - x) {f} dydt = x*(rho - z) - y {g} dzdt = x*y - bet*z {k} */ #include<iostream> #include<cmath> #include<fstream> #include <iomanip> using namespace std; double sig =

问题 I wrote the code to solve Lorenz equations using RK-4 method in C++. I have to plot the attractor plot and I have some difficulty in solving the 3 first order coupled differential equation using RK-4 method. Here is my code: /* Solving 3 coupled first order differential equations using RK4 for the Lorentz system dxdt = sig*(y - x) {f} dydt = x*(rho - z) - y {g} dzdt = x*y - bet*z {k} */ #include<iostream> #include<cmath> #include<fstream> #include <iomanip> using namespace std; double sig =

问题 Population over time (should be the same height at every peak I've programmed a code to simulate a mice and fox population using Runge-Kutta 4th order. But the result is not as wanted to be.. each peak should nearly be at same height I don't think that it is a problem of step size.. Do you have an idea? import matplotlib.pyplot as plt import numpy as np #function definition def mice(f_0, m_0): km = 2. #birthrate mice kmf = 0.02 #deathrate mice return km*m_0 - kmf*m_0*f_0 def fox(m_0, f_0): kf

问题 I'm working on a trajectory calculator for the Two Body Problem, and I'm attempting to use Scipy's RK45 or LSODA to solve the ODE and return the trajectory. (Please suggest another method if you think there's a better/easier way to do this) I'm using the Spyder IDE with Anaconda. Scipy version 1.1.0 THE PROBLEMS: RK45: When using RK45, the first step seems to work. When stepping through the code in the debugger, twoBody() is entered, and works exactly as expected the first run through.