Engineering Notes -- Home


A note from the author

As a practicing aerospace engineer, I frequently encounter problems that require math skills I don’t have and must learn. Early in my career I adopted the habit of writing down the solutions to these problems in a personal Engineering Notebook. If a problem took more than a trivial amount of time to research, and was general enough that I might run into it again some day, into the notebook it went.

The articles on this website are based on those engineering notes. They represent practical, battle-tested solutions to real-world problems. Technology changes, but math is eternal. I hope these papers save you some time.



Globe Image

Converting between Earth-Centered, Earth Fixed and Geodetic Coordinates

How to convert from Geodetic coordinates (latitude, longitude and height above ellipsoid) to Earth-Centered, Earth-Fixed coordinates, and back again. Includes example code.

2D Rotation Image

Rotating Points in Two-Dimensions

The efficient way to rotate points around an arbitrary center on a two-dimensional Cartesian plane.

3D Rotation Image

Rotations in Three-Dimensions: Euler Angles and Rotation Matrices

Describes a commonly used set of Tait-Bryan Euler angles, and shows how to convert from Euler angles to a rotation matrix and back.

Quaternion image

Rotation Quaternions, and How to Use Them

An introduction to rotation quaternions. Shows how to perform rotations, and how to convert between quaternions, rotation matrices, axis-angle, and Euler angles.

Line crossing image

Solving 2x2, 3x3, 4x4 and 5x5 Systems of Linear Equations on a Computer

A general solution to systems of linear equations of up to 5 equations and 5 unknowns, using Cramer's Method.

Interpolated sampled waveform image

Interpolation

Methods for interpolating one-dimensional signals, images, and 2D graphics. Based on Catmull-Rom cubic spline.

Registering Images

Rigid-Body Image Registration

A tiepoint-based error-minimization method for registering two images, where the degrees of freedom are limited to translation, rotation and scale.


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