diff --git a/.gitignore b/.gitignore index 79efed8..195baec 100644 --- a/.gitignore +++ b/.gitignore @@ -38,3 +38,7 @@ *.bib *.synctex.gz *.bbl + +# C++ specifics +src/* +!src/*.cpp diff --git a/latex/assignment_1.pdf b/latex/assignment_1.pdf index 2446e3b..712e889 100644 Binary files a/latex/assignment_1.pdf and b/latex/assignment_1.pdf differ diff --git a/latex/problems/problem1.tex b/latex/problems/problem1.tex index 779a58f..8f53c11 100644 --- a/latex/problems/problem1.tex +++ b/latex/problems/problem1.tex @@ -1,8 +1,17 @@ \section*{Problem 1} +First, we rearrange the equation. + +\begin{align*} + - \frac{d^2u}{dx^2} &= 100 e^{-10x} \\ + \frac{d^2u}{dx^2} &= -100 e^{-10x} \\ +\end{align*} + +Now we find $u(x)$. + % Do the double integral \begin{align*} - u(x) &= \int \int \frac{d^2 u}{dx^2} dx^2\\ + u(x) &= \int \int \frac{d^2 u}{dx^2} dx^2 \\ &= \int \int -100 e^{-10x} dx^2 \\ &= \int \frac{-100 e^{-10x}}{-10} + c_1 dx \\ &= \int 10 e^{-10x} + c_1 dx \\ @@ -10,7 +19,7 @@ &= -e^{-10x} + c_1 x + c_2 \end{align*} -Using the boundary conditions, we can find $c_1$ and $c_2$ as shown below: +Using the boundary conditions, we can find $c_1$ and $c_2$ \begin{align*} u(0) &= 0 \\ diff --git a/latex/problems/problem3.tex b/latex/problems/problem3.tex index 2d7ab8b..da9188e 100644 --- a/latex/problems/problem3.tex +++ b/latex/problems/problem3.tex @@ -2,7 +2,7 @@ \section*{Problem 3} To derive the discretized version of the Poisson equation, we first need -the taylor expansion for $u(x)$ around $x + h$ and $x - h$. +the Taylor expansion for $u(x)$ around $x$ for $x + h$ and $x - h$. \begin{align*} u(x+h) &= u(x) + u'(x) h + \frac{1}{2} u''(x) h^2 + \frac{1}{6} u'''(x) h^3 + \mathcal{O}(h^4) @@ -24,8 +24,8 @@ If we add the equations above, we get this new equation: We can then replace $\frac{d^2u}{dx^2}$ with the RHS (right-hand side) of the equation: \begin{align*} - - \frac{d^2u}{dx^2} &= 100 e^{-10x} \\ - \frac{ - u_{i+1} + 2 u_i - u_{i-1}}{h^2} + \mathcal{O}(h^2) &= 100 e^{-10x} \\ + - \frac{d^2u}{dx^2} &= f(x) \\ + \frac{ - u_{i+1} + 2 u_i - u_{i-1}}{h^2} + \mathcal{O}(h^2) &= f_i \\ \end{align*} And lastly, we leave out $\mathcal{O}(h^2)$ and change $u_i$ to $v_i$ to @@ -33,5 +33,5 @@ differentiate between the exact solution and the approximate solution, and get the discretized version of the equation: \begin{align*} -align* \frac{ - u_{i+1} + 2 u_i - u_{i-1}}{h^2} &= 100 e^{-10x} \\ + \frac{ - v_{i+1} + 2 v_i - v_{i-1}}{h^2} &= 100 e^{-10x_i} \\ \end{align*}