# Graph an equation without x or y variables

Can not find information on how to graph an equation that does not contain x or y variables. Trying to graph the following equation:
N= (v*12) /(3.1415 * D)
Will assign D a value from a dropdown list.
How do I assign the N and v variables to the x and y axis.

Hi,

Welcome to the community!

You need to create a range of values for `v`, then apply the equation for `N`. One way to do it in js is:

``````const range = (start, stop, step) => {
let v=start
const array = []
while(v <= stop){
array.push(v);
v=v+step
}
return array;
}

// For example
const v = range(0, 10, 0.5);
const Nfunc = (v, D) => 12 * v / (Math.PI * D); // I assume you want Pi = 3.1415....

// Then...
const N = v.map(x => Nfunc(x, D));
``````

Thanks,
Still having trouble making this work. Need a complete working example with html, script code.

Try this:

``````<head>
<script src='https://cdn.plot.ly/plotly-2.11.1.min.js'></script>

<body>
<div id='myDiv'></div>
</body>

<script>
const range = (start, stop, step) => {
let v=start
const array = []
while(v <= stop){
array.push(v);
v=v+step
}
return array;
}

// For example
const D = 1.0;
const v = range(0, 10, 0.5);
const Nfunc = (v, D) => 12 * v / (Math.PI * D); // I assume you want Pi =   3.1415....

// Then...
const N = v.map(x => Nfunc(x, D));

const trace1 = {
x: v,
y: N,
mode: 'markers',
type: 'scatter'
};

const data = [trace1];

Plotly.newPlot('myDiv', data);
</script>
``````

Still getting a JavaScript error that range is not defined.

``````<!DOCTYPE html>
<html>

<script src='https://cdn.plot.ly/plotly-2.11.1.min.js'></script>

<body>
<div id='myDiv'></div>
</body>

<script>

// For example
const D = 1.0;
const v = range(0, 10, 0.5);
const Nfunc = (v, D) => 12 * v / (Math.PI * D);

// Then...
const N = v.map(x => Nfunc(x, D));

const trace1 = {
x: v,
y: N,
mode: 'markers',
type: 'scatter'
};

const data = [trace1];

Plotly.newPlot('myDiv', data);
</script>
</html>
``````

Yeah, but you deleted this part from my exampleâ€¦

Thanks,
That worked.