Mathematics is an abstraction. Instead of thinking about particular numbers, mathematics focuses on the underlying patterns.
This note contains basic math formulas and terms that I mix up on a semi-regular basis.
- Theorem: A pattern or rule.
- Proof: Calculations that show that a theorem is always true.
- Center: Every point of a circle have the same distance from this point.
- Edge: Points that form the outline of a circle.
- Radius: Distance from the center to the edge.
- Circumference: Distance of the edge.
- Diameter: Distance from an edge point to opposite point. Twice the radius.
- Pi: Ratio between circumference and diameter. Always 3.141559...
Average (Arithmetic Mean): The sum of a collection of values divided by the number of values in the collection.
sum(x) / x.length
Mid-range: Average of the minimum and maximum values in a collection.
( max(x) + min(x) ) / 2
Median: The middle value in an ordered collection of value. If there is a even number of numbers, median is average of the two middle numbers.
x = [a, b, c, d, e] ^ ^ ^ min. med. max.
Mode: The most common value in a collection of values.
x[a, a, b, c, c, b, b] = Mode is b
Quadratic is a generalization of conic sections such as ellipses, circles, parabolas and hyperbolas. Think of a 3D cone where you cut slices.
Transpose is flipping matrix rows to columns and columns to rows over its the diagonal,
Ordinal data is a categorical data type where the variables have ordered categories and the distances between the categories are not known.