node-red-contrib-curve/curve/locales/en-US/curve.html

Node to calculate output by a given mathematical function expression

<script type="text/x-red" data-help-name="curve" data-lang="en-US">
    <p>
        A function node for a mathematical expression f(x) for creating simulation data, characteristics, calibration data and other
        numerical output based on a numeric input.

        <ol>
            <li>
                easy expression formula like x^2, sqrt(x), nthRoot(x), exp(x), sin(x), cos(x) etc. (see <a href="http://maurizzzio.github.io/function-plot/"
                    target="_blank">function-plot</a>)
            </li>
            <li>
                define which property from <code>msg</code> to use for x value input
            </li>
            <li>
                use Mustache-Syntax to include variables from <code>msg</code> or <code>context</code>
            </li>
            <li>
                Use the modulo-operator (%) to create infinite ranged functions like <a href="http://easings.net/" target="_blank">easings</a>.
            </li>
        </ol>
    </p>
    <h3>Examples</h3>
    <dl>
        <dt>easeOutElastic</dt>
        <dd>-0.5*exp(-6x)*(-2*exp(6x) + sin(12x) + 2cos(12x))</dd>
        <dt>easeOutQuad</dt>
        <dd>-{{change}}*(x/{{duration}})*(x-2)+{{start}}</dd>
        <dt>easeInOutQuad</dt>
        <dd>((2*x/{{duration}})
            <1)*({{change}}*0.5*x*x) + (2*x/{{duration}}>=1)*-0.5*{{change}}*((x-1)*(x-3)-1) + {{start}}</dd>
    </dl>

    <h3>Inputs</h3>
    <dl class="message-properties">
        <dt>payload <span class="property-type">number</span></dt>
        <dd> the ordinal x of the function to calculate the result from. </dd>

        <dt class="optional">function <span class="property-type">string</span></dt>
        <dd> if defined will overwrite the node's defined function</dd>

        <dt class="optional">topic <span class="property-type">string</span></dt>
        <dd> the MQTT topic to publish to.</dd>
    </dl>

    <h3>Outputs</h3>
    <ol class="node-ports">
        <li>Standard output
            <dl class="message-properties">
                <dt>payload <span class="property-type">number</span></dt>
                <dd>The result of the function calculation. Returns NaN if x was out of defined range.</dd>

                <dt>topic <span class="property-type">string</span></dt>
                <dd>A copy of any inbound topic if present. Otherwise, the topic from the node's settings.</dd>
            </dl>
        </li>
    </ol>

    <h3>Node Settings</h3>
    <dl>
        <dt>Value x</dt>
        <dd>The property from <code>msg</code> to use for the value x for the function input</dd>
        <dt>Function</dt>
        <dd>
            A function f(x) defined according to <a href="https://github.com/maurizzzio/built-in-math-eval" target="_blank">built-in-math-eval</a>            as a function expression. You can use Mustache-Syntax to include values from the <code>flow</code> or <code>global</code>            context or <code>msg</code>. The function would then be reevaluated on each input.

        </dd>
        <dt>Name</dt>
        <dd>A short description shown in the admin interface</dd>
        <dt>Topic</dt>
        <dd>A topic name to use if the incoming msg does not contain one.</dd>
    </dl>

    <h3>Performance</h3>
    <p>
        The node is most performant when not using Mustache-Syntax or redefine function expression via msg.function as this leads
        to an recompilation of the function expression with each incoming <code>msg</code>. There is currently no
        function expression cache. This node will reuse the incoming <code>msg</code> for its output.
    </p>>
    <p>
        Note: to gain more performance use a function-node for calculation. This is more a convenient node for easier setup of curves.
    </p>

    <h3>Details</h3>
    <p>
        When using Mustache-Syntax these values will be replaces bei "0" for the preview window, so function may not get plotted
        correctly. You can use the node-red-contrib-counter node to create a continous input stream of (0,1,2,4,5,6...).
        For more information, see the GitHub page for <a href="https://github.com/sbarwe/node-red-contrib-curve">node-red-contrib-curve</a>
    </p>
    <p>
        This node uses the work of Mauricio Poppe for visualization and function expression parsing. This node-red node is just a
        wrapper around this library.
    </p>
</script>