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# JavaScript - Math.exp() method example

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`Math.exp()` is a static method that takes only one parameter and return exponential function value in the range `0` (exclusive) to `+Infinity`.

``````// ONLINE-RUNNER:browser;
console.log( Math.exp(      -100 ) ); // 3.720075976020836e-44
console.log( Math.exp(        -1 ) ); // 0.36787944117144233
console.log( Math.exp(         0 ) ); // 1
console.log( Math.exp(         1 ) ); // 2.718281828459045
console.log( Math.exp(       100 ) ); // 2.6881171418161356e+43

console.log( Math.exp( -Infinity ) ); // 0
console.log( Math.exp( +Infinity ) ); // Infinity
console.log( Math.exp(       NaN ) ); // NaN``````

## 1. Documentation

 Syntax `Math.exp(number)` Parameters `number` - integer or float number value (primitive value). Result Exponential function value of a number in the range `0` (exclusive) to `+Infinity` (primitive value). If the value can not be calculated `NaN` is returned. Description `Math.exp()` is a static method that takes only one parameter and returns exponential function value.

## 2. Reversed console plot example

``````// ONLINE-RUNNER:browser;

var x1 = -4; // beginning of sine chart
var x2 = +2.8; // end of sine chart

var y1 = -1.0;
var y2 = +10.0;

var xSteps = 25;
var ySteps = 60;

var dx = (x2 - x1) / xSteps; // x axis step
var dy = (y2 - y1) / ySteps; // y axis step

function printLine(y1, y2, character) {
var line = '';

for(var y = y1; y < y2; y += dy) {
line += ' ';
}

console.log(line + character);
}

if (y <= y1 || y >= y2) {
console.log(' ');
} else {
printLine(y1, y, '+');
}
}``````

## 3. Canvas plot example

``````// ONLINE-RUNNER:browser;

<!doctype html>
<html>
<style> #canvas { border: 1px solid black; } </style>
<body>
<canvas id="canvas" width="200" height="300"></canvas>
<script>

var canvas = document.querySelector('#canvas');
var context = canvas.getContext('2d');

// exponential function chart range
var x1 =  -0.1;
var x2 =  +5.0;
var y1 =  -0.1;
var y2 = +10.0;

var dx = 0.1;

var xRange = x2 - x1;
var yRange = y2 - y1;

var yScale = 0.1;

function calculatePoint(x) {
var y = Math.exp(x) * yScale;

// chart will be reversed horizontaly because of reversed canvas pixels

var nx = (x - x1) / xRange;       // normalized x
var ny = 1.0 - (y - y1) / yRange; // normalized y

var point = {
x: nx * canvas.width,
y: ny * canvas.height
};

return point;
}

console.log('x range: <' + x1 + '; ' + x2 + '>');
console.log('y range: <' + y1 + '; ' + y2 + '>');

var point = calculatePoint(x1);

context.beginPath();
context.moveTo(point.x, point.y);

for (var x = x1 + dx; x < x2; x += dx) {
point = calculatePoint(x);
context.lineTo(point.x, point.y);
}

point = calculatePoint(x2);
context.lineTo(point.x, point.y);
context.stroke();

</script>
</body>
</html>``````

## References

1. Exponential function - Wikipedia

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