## Usage:

function1 + function2 : (function, function) -> function interval1 + interval2 : (range, range) -> range interval1 + constant : (range, constant) -> range interval1 + constant : (constant, range) -> range

## Parameters:

• function1 and function2 represent functions
• interval1 and interval2 represent intervals (ranges)
• constant represents a constant or constant expression

## Description:

• + represents the addition (function) on reals. The expression function1 + function2 stands for the function composed of the addition function and the two functions function1 and function2.
• + can be used for interval arithmetic on intervals (ranges). + will evaluate to an interval that safely encompasses all images of the addition function with arguments varying in the given intervals. Any combination of intervals with intervals or constants (resp. constant expressions) is supported. However, it is not possible to represent families of functions using an interval as one argument and a function (varying in the free variable) as the other one.

> 1 + 2;
3

> x + 2;
2 + x

> x + x;
x * 2

## Example 4:

> diff(sin(x) + exp(x));
cos(x) + exp(x)

## Example 5:

> [1;2] + [3;4];
[4;6]
> [1;2] + 17;
[18;19]
> 13 + [-4;17];
[9;30]