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Category Archives: Complex numbers

Roots on the complex plane

I derive in detail the specific form of 2D Newton-Raphson for a simple root-finding problem on the complex plane. Try it out and create your own fractals!Video. Notes.

Posted byjoaquindrutJanuary 25, 2023January 25, 2023Posted inComplex numbers, Numerical methods

Green’s function for diffusion in 1D. Part 2.

I finalize the discussion started in Part 1 with an example showing the behavior for a specific source, which is a simple Gaussian in space and in time. I comment on how to make sure the desired initial conditions are satisfied by adding a solution to the homogeneous equation. Video. Notes.

Posted byjoaquindrutJanuary 3, 2023January 3, 2023Posted inComplex numbers, Fourier series and transforms, Green's functions

Green’s function for diffusion in 1D. Part 1.

I solve for the Green’s function of the diffusion operator on the whole real line. To that end, I use Fourier transforms in space and time and contour integration (more on that later!).Video. Notes.

Posted byjoaquindrutJanuary 1, 2023January 1, 2023Posted inComplex numbers, Fourier series and transforms, Green's functions

The quantum free particle

Using background on complex numbers and Fourier modes, here is a first discussion of the most essential quantum mechanical system. Video. Notes.

Posted byjoaquindrutDecember 6, 2022Posted inComplex numbers, Fourier series and transforms, Linear algebra, Quantum mechanics

Euler’s formula

A quick look at the derivation of Euler’s formula and its uses and connections to trigonometric and hyperbolic sine and cosine functions of complex variables. Video. Notes.

Posted byjoaquindrutDecember 2, 2022December 2, 2022Posted inComplex numbers

Complex numbers basics

Definition and basic properties of complex numbers. Addition, multiplication, division, conjugation. Polar representation. Trigonometric identities. Differentiation & Cauchy-Riemann conditions. Simple examples. Video. Notes.

Posted byjoaquindrutDecember 1, 2022Posted inComplex numbers

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