# The Evaluate Command

The Evaluate command is used to do numeric evaluation of expressions. It is used on expressions that can be evaluated to a single numeric value. It can also act on Boolean expressions like "True & False" and on certain relationships between types. The keystroke for the Evaluate command is the "a" key.

The Evaluate command acts on basic mathematical objects like addition, subtraction, multiplication, division, powers and roots when the terms in these expression are numerical values. In complicated expressions, not all of the terms have to be numeric for the Evaluate command to work. The command will evaluate any terms in the overall expression that can be evaluated to a numeric result.

Note that while the Simplify command will simplify 2/4 to 1/2, the Evaluate command will reduce it to 0.5. This is implemented this way because we typically would want 1/2(x + 2x + y) to simplify to 1/2(3x + y) not 0.5(3x + y).

On expressions that involves Real numbers the Simplify command and the Evaluate command typically produce the same result. So if we have 3.4*7*x, both Simplify and Evaluate will produce 23.8*x.