He was able to solve the complex calculation quickly.

He was calculating in his head.

He notched an arrow on his bow.

I live in Ya.

In ancient wars, arrows were the main weapon.

He ate half of the pizza.

He rolled the dice, but it came up odd.

I ate half of the pizza.

A positive-semidefinite matrix is one of the important concepts in linear algebra.

You can solve the problem by using this method.