TABLE OF CONTENTS | ?, ? | delta |
| ? | epsilon (commonly used to represent small numbers) |
| ? | theta (a variable angle) |
| ? | mu (often represents measures) |
| ? | xi (a variable representing the wave number, or spatial frequency, for Fourier transforms of signals that depend on x, representing space) |
| ? | sigma (standard deviation) |
| ? | tau (a variable representing frequency, for Fourier transforms of signals that depend on t, representing time.) |
Note: k often replaces ? or ? in formulas for Fourier series, according to the mathematical convention that k represents integer variables, while ? and ? represent continuous variables.
| ? or ? | phi (the scaling function; also used to represent the phase angle) |
| ? | psi (the wavelet; in quantum mechanics, the wave function) |
| ? | sum |
| ? | integral |
| ? | product |
| ? | union |
| ? | intersection |
| ? | infinity |
The trigonometric functions we use in this book are sine (abbreviated sin) and cosine (abbreviated cos). Consider a unit circle (a circle with radius 1) centered at 0: x 2+ y 2 = 1. Starting from the point (1,0), go a distance ? counterclockwise,...
