Beginner Topic 3 of 51 Math for Computing
Exponents and Logarithms
Powers and their inverses, central to complexity.
How it works
An exponent says how many times to multiply a base by itself, with rules such as a to the m times a to the n equals a to the m plus n, and negative and fractional exponents meaning reciprocals and roots. A logarithm is the inverse: log base b of x is the exponent to which b must be raised to give x. Logs turn multiplication into addition, log of xy equals log x plus log y, and powers into multiplication, with change-of-base formula allowing conversion. Common bases are 2, e and 10.
Where it is used
Algorithm analysis uses log n for binary search and tree height, information theory measures bits with log base 2, compound growth and decay, decibel scales, and machine-learning loss functions use logs and exponentials.
Common pitfall
Log of a sum is not the sum of logs, a classic error. Logs are defined only for positive arguments. Different bases differ by constant factors, which is why Big-O ignores the base. Floating-point underflow in products of small probabilities is avoided by adding logs.
Where it fits in the course
Exponents and Logarithms is topic 3 of 51 in Math for Computing, rated Beginner. It follows Algebra Review. The next topic is Summations and Series.
Practice and explore
- Open the interactive lesson, with a mini quiz.
- Take the Math for Computing quiz.
How to study this topic
- Read the explanation above and restate the definition in your own words.
- Open the interactive lesson and answer its mini quiz.
- Read the common pitfall, then write a short example that avoids it.
- Check your understanding in the Math for Computing quiz, and revisit the topic if you miss a question.
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Related topics
- Algebra Review (Math for Computing)
- Summations and Series (Math for Computing)
- Number Systems (Math for Computing)
- Functions and Graphs (Math for Computing)