conf, set_conf

Gamma: Version 4.0
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# `conf`, `set_conf`

`conf`, `set_conf` -- query and set confidence factors.

## Syntax

    conf (s_exp)
    set_conf (s_exp, number|s_exp)

## Arguments

`s_exp`

  Any Gamma or Lisp expression.

`number`|`s_exp`

  Any number, or any expression that evaluates to a number. Non-numbers are treated as zero.

## Returns

The confidence factor of the `number` or `s_exp`.

## Description

All Gamma and Lisp expressions in Gamma have an associated confidence factor between 0 and 100 which may be queried using the `conf` function. This is typically 100, or fully confident. Exceptions arise only when the user explicitly sets the confidence to another value, or when a datahub provides a confidence value to the interpreter. The `set_conf` function will set the confidence of an expression to any numerical value, though legal values are between 0 and 100. Numbers less than 0 indicate indeterminate confidence. Numbers greater than 100 will produce strange results.

## Example

        Gamma> x = 3;
        3
        Gamma> set_conf(x, 40);
        40
        Gamma> conf(x);
        40
        Gamma>

See the PID Controller Class section of the PID Emulator chapter in the Cogent Tools Demo and Tutorials book for an example of this function used in context.

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