Glossary · Phase 2 · Math, when you need it
Subscript
A small letter or number written low after a name to mark a position: xᵢ is the i-th x, written x[i] in Python.
A small letter or number written low after a name is a subscript: xᵢ is "the i-th x", and x₂ is the second one. In code, that's indexing:
x[i]. Two subscripts mean a table: Wᵢⱼ is row i, column j, which isW[i][j].
Try it now
A phrasebook in three groups: symbols that loop over many values, symbols that mark a special number, and symbols that compare.
Learn it properly
Reading math notation as code · Σ, subscripts, hats and bars, translated into Python you can run and test. About 25 minutes.
Other terms from the same lesson
- argmax: The input that makes a value biggest, rather than the biggest value itself. The argmax of a classifier's scores is the winning class.
- summation: Adding up a list of values, written with the Greek letter Σ: Σ xᵢ means add every xᵢ. In code it's a loop with a running total, or sum().
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