differential equations for dummies

Ordinary differential equations Derivative that contains an unknown function, such as The equation is a differential equation. In general, the equation that represents the relationship between the derivative of an unknown function, an unknown function, and an independent variable is called a differential equation. The

9. Matrix Differential Equations I. Matrix differentiation and integration 1. Matrix derivative definition: if each element of the matrix is A microfunction of variable t, it is called A (t). Its derivative is defined As a result, a function can define a higher-order derivative, similarly, a partial derivative. Matrix derivative properties: If A (t) and B (t) are two micro-matrices that can be computed a

Updated: 9 APR 2016======== Method ========For arbitrary two-element order homogeneous linear partial differential equations, \ (a_{11}\dfrac{\partial^2u}{\partial x^2}+2a_{12}\dfrac{\partial^2 u}{\partial x\partial y}+a_{22}\dfrac{\partial^ 2 u}{\partial y^2}+b_1\dfrac{\partial u}{\partial x}+b_2\dfrac{\partial u}{\partial y}+cu=0\) The method of finding the characteristic equation, determining the classif

differentiation. In fact, in the well-known Photoshop image processing software, its stain Repair Tool is implemented by using the PDDE. Image repair can be basically divided into two categories. First, it is better to fix small cracks. Another type is the repair of large blocks of holes, which are usually filled with textures. In Photoshop, choose fill> Texture Recognition to implement the texture Filling Algorithm for large blocks. The PS algorithm is not satisfactory for many times for fil

There are a lot of classic formulas in physics and math, these formulas can be very complex to edit, but if we can easily edit these formulas by using MathType, let's take the differential form of maxwells equations as an example and introduce how to enter them in MathType.If you have any questions, you can visit:http://www.mathtype.cn/jiqiao/maikesiwei-fangcheng.htmlDifferential form of Maxwells equation

1. Steps to solve ordinary differential equations: fromSymPyImport*init_printing ()#define symbolic Constants X with F (x) g (x). The f G here can also be replaced with other letters to represent the functionx = Symbol ('x') F, G= Symbols ('F G', cls=Function)#using Diffeq to represent differential equations: F ' (x)?

1.MATLAB you can use the limit command to calculate limits.>> syms X>> Limit ((x^3 + 1)/(X^4 + 2))Ans =1/22. We can call the isequal command in MATLAB to check whether two quantities are equal, and if two are not equal, IsEqual returns 0.3. We use the following syntax to calculate the limit in Limx→∞f (x) Form: Limit (F,inf).4. Calculate the left and right limits: we have to pass the function to calculate the limit of the variable and the "Leave", "right" string, separated by commas.5. By invoki

{\p \rho}{\p T} +\rho_0\sum_{i=1}^3 \cfrac{\p v_i}{\p x_i}=0,\\ \cfrac{\p v_k}{\p T} +\cfrac{p ' (\rho_0)}{\rho_0}\cfrac{\p \rho}{\p x_k}=0,\ k=1,2,3 \ea} \eex$$ is a hyperbolic equation group where $\rho_0>0$, $p ' (\rho) >0$ are Constant.Answer: Consider the $t $ as the fourth independent variable, consider $\rho$ as the fourth dependent variable, $$\bex \sedd{\ba{ll} \cfrac{p ' (\rho_0)}{\rho_0}\cfrac{\p \rho}{\p X_k} +\cfrac{\p V _k}{\p t}=0,\ k=1,2,3\\ \rho_0\sum_{i=1}^3 \cfrac{\p v_i}{\p x

The graduation design of the undergraduate project "The application of Laguerre wavelet in numerical integration and numerical solution of differential equation" is to approximate the function that needs integral or solve differential equation by Laguerre wavelets function, the original function is difficult to obtain the function is expressed by the wavelet function, so it is easy to solve the numerical in

MATLAB solves the delayed differential equation. dde23 call format: Sol = dde23 (ddefun, lags, history, tspan ); -- Ddefun function handle, solving the Differential EquationY' = f (t, y (t), y (t-Tau 1),..., y (t-Tau k )) It must be written in the following format: Dydt = ddefun (T, y, z ); T corresponds to the current time t, and Y is the column vector, which is similar to Y (t); Z (:, j) is similarY (t-Ta

Algorithm code Solinit = bvpinit (linspace (, 5), [1 0]); % linspace (, 5) is the initial mesh, [] is the initial estimated value Sol = bvp4c (@ twoode, @ twobc, solinit); % twoode and twobc are the functions of the differential equation and the boundary condition, respectively, solinit is structured X = linspace (); % determines the X range y = Deval (sol, x); % determines the y range plot (X, Y (1 ,:)); % plot the graph % of Y-X to define the two

) $ \ Mit L ^ {p} (\ Omega) $ \ (\ subset \ mathcal {d'} (\ Omega )\), but $ \ mathcal {d'} (\ Omega) \ not \ subset \ mit L ^ {p} (\ Omega), p \ Ge, 1. $Proof: Step 1 proof $ \ forall L \ [\ In \ mit L ^ {p} (\ Omega) $ is on $ \ mathcal {d} (\ Omega) $ linear functional; \]\ Begin {Align}L (v) = L (\ alpha_1 v_1 + \ alpha_2 V_2) = =\ Alpha_1 =\ Alpha_1l (v_1) + \ alpha_2l (V_2), \ forall \ alpha_1, \ alpha_2 \ In \ r, v_1, v_2 \ In \ mathcal {d} (\ Omega ).\ End {Align}$? Step 2 proves

"Reprint Please specify source" Http://www.cnblogs.com/mashiqi2015/09/08Today we focus on the following equation:$ $u ' =au, \textrm{where} (a > 0) $$Due to $a > 0$, $ (U '-\sqrt{a}u) ' + \sqrt{a} (U '-\sqrt{a}u) =0 \rightarrow \frac{d (U '-\sqrt{a}u)}{u '-\sqrt{a}u}=-\sqrt{ a}dx$. Therefore $u '-\sqrt{a}u = C e^{-\sqrt{a}x}$. This is a first-order linear ordinary differential equation.Let $u (x) = f (x) e^{-\sqrt{a}x}$, we can get $f ' -2\sqrt{a}f=c

{d} (\ Omega) \), \ (| v | _ k = \ sup _ {\ Omega} | V (X) |, \, V \ In \ mathcal {d} (\ Omega ). \) (you can prove it yourself) $ \ Mit L ^ {p} (\ Omega) $ \ (\ subset \ mathcal {d'} (\ Omega )\), but $ \ mathcal {d'} (\ Omega) \ not \ subset \ mit L ^ {p} (\ Omega), p \ Ge, 1. $Step 1 proves that $ \ forall L \ In \ mit L ^ {p} (\ Omega) $ is a linear functional of \ (\ mathcal {d} (\ Omega;\ [\ Begin {Align *} l (v) = Step 2 proves that \ (L \) is continuous, that is, proof \ (| L (V) |

1. There is a soft uniform thin line, in the damping medium for small transverse vibration, the unit length chord resistance $F =-ru_t$. The vibration equation is deduced.Answer: $$\bex \rho u_{tt}=tu_{xx}-ru_t. \eex$$2. The three-dimensional heat conduction equation has the spherical symmetry form $u (x,y,z,t) =u (r,t) $ ($r =\sqrt{x^2+y^2+z^2}$) solution, trial: $$\bex U_t=a^2\sex{u_{rr}+\frac{2u_r}{r}}. \eex$$Proof: by $$\bex U_x=u_r\frac{x}{r},\quad u_{xx}=u_{rr}\frac{x^2}{r^2} +u_r\frac{r-x