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Solving for streamlines from numerical velocity field
Say I have a given numerical velocity field in two dimensions, (u,v). I am trying to find the streamlines from this data set at a particular contour level...
Apr 11, 2026
Archive: News
news
Triangular arrays and almost sure convergence of row averages
Suppose we have the triangular array $\{\{X_{in},i=1,\ldots,n\},n=1,2,\ldots\}$: $$\begin{array}{ccccc} X_{11}&&&&\\ X_{12}&X_{22}&...
Apr 11, 2026
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inhomogeneous heat equation with mixed boundary conditons
Solve $$U_{t}=U_{xx}+u$$ with mixed boundary conditions $$U_x(0,t)=0, U(l,t)=0$$ and initial condition $$U(x,0)=\varphi(x)$$ I know that I have to use sep...
Apr 11, 2026
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constructing a matrix given its column space and null space
This is not homework, class or a project. I've been out of college for some time now and decided to learn math on my own time. I can't figure ou...
Apr 11, 2026
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Why divergence of radius vector equals 3?
Ok, I know $div \vec r=3$. $\vec r = r_x\vec i+r_y\vec j + r_z\vec k$. $(\frac{\partial}{\partial x}i+\frac{\partial}{\partial y}j+\frac{\partial}{\partia...
Apr 11, 2026
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Understanding Quadratic Variation
I think part of the trouble a lot of people (or at least me personally) have with making the jump from calculus to stochastic calculus is the notion of qu...
Apr 11, 2026
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Minimize using simplex method with mixed constraints
Using the simplex method, minimize $z= -2x_1+12x_2-3x_3-5x_4-x_5$ with $x_i \geq 0$ and subject to constraints: $x_1+4x_3-5x_4+2x_5 \leq 4$ $4x_2-x_4 \leq...
Apr 11, 2026
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Convert a equation with fractions into whole numbers
So I have this equation: $$\frac{2}{3}a^2-\frac{4}{9}a^2 = 8a$$ So this is a really easy problem, I could just multiply $$\frac{2}{3}*\frac{3}{3} = \frac{...
Apr 11, 2026
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annihilator method confusion
I have a final in the morning and I am extremely confused on the annihilator method. I have been googling different explanations all night and I just dont...
Apr 11, 2026
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Does there exist an even polynomial that has a term with an odd power?
Does there exist an even polynomial (i.e. $f(-x)=f(x)$ for all $x$) that has at least one odd power of $x$?
Apr 11, 2026
