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Matrices
A matrix is a grid of numbers; a stack of vectors.
Transcript
A matrix is a grid of numbers.
This one has two rows, and three columns. We call it two by three.
Read it down, and each column is a vector. One, two, three vectors, side by side.
Read it across, and each row is a vector too, lying on its side.
Every entry has an address: row first, then column. Row two, column three holds a seven.
Matrices come in any shape. Tall, wide, or square.
A matrix with just one column is simply a vector.
A grid of numbers, or vectors side by side. Same thing.
Needs
- Vectors video
A vector is a list of numbers, and also an arrow.
Leads to
- Matrix times vector video
Each output entry is a dot product of one row with the vector. - Transpose video
Flip a matrix so rows become columns.