up one level

# Table of Contents

## Expressions

Expressions equations that are implemented within the OreTek system incorporating variables to perform modifications on devices. These equations are clustered into codes which can then be entered into prescriptions. Values to the left of an = sign must match a database field so that there is an allocation available for it.
+ addition
Returns the sum of 2 or more values
- Subtraction
Returns the difference of 2 or more values
* multiplication
Returns the product of 2 or more values
/ division

^ power
Returns the power of the value. For root expressions, values less than 1 can be implemented.
Example: squareroot(2) = 2^ 0.5
> Greater value
Returns the higher of 2 values

ptadd=ptadd>(a0depth+0.5)

In the above example, the higher value of ptadd and a0depth+0.5 is returned. Greater Value and lower value expressions have the same priority as addition and subtraction. As a result, often () are used to reestablish the priority of the equation.
< Lower value

() Priority of equations
In any equation, certain intuitive priorities are lost in interpretation.

Consider the following:

y=mx+b
x = y-b/m
When written, understood is that x = (y-b)/m . The expression evaluator however sometimes needs help in re-prioritizing the expression to what is desired. Without (), the returned value would return y-(b/m), which is clearly wrong.
Log() Natural Logrithm
Replaces the expression with the natural logrithm of the value.