# Square Root of Epsilon
> [Square root][@stdlib/math/base/special/sqrt] of [double-precision floating-point epsilon][@stdlib/constants/float64/eps].
## Usage
```javascript
var FLOAT64_SQRT_EPSILON = require( '@stdlib/constants/float64/sqrt-eps' );
```
#### FLOAT64_SQRT_EPSILON
[Square root][@stdlib/math/base/special/sqrt] of [double-precision floating-point epsilon][@stdlib/constants/float64/eps].
```javascript
var bool = ( FLOAT64_SQRT_EPSILON === 0.14901161193847656e-7 );
// returns true
```
## Examples
```javascript
var abs = require( '@stdlib/math/base/special/abs' );
var max = require( '@stdlib/math/base/special/max' );
var randu = require( '@stdlib/random/base/randu' );
var FLOAT64_SQRT_EPSILON = require( '@stdlib/constants/float64/sqrt-eps' );
var bool;
var a;
var b;
var i;
function isApprox( a, b ) {
var delta;
var tol;
delta = abs( a - b );
tol = FLOAT64_SQRT_EPSILON * max( abs( a ), abs( b ) );
return ( delta <= tol );
}
for ( i = 0; i < 100; i++ ) {
a = randu() * 10.0;
b = a + (randu()*5.0e-7) - 2.5e-7;
bool = isApprox( a, b );
console.log( '%d %s approximately equal to %d. Delta: %d.', a, ( bool ) ? 'is' : 'is not', b, abs( a - b ) );
}
```
[@stdlib/math/base/special/sqrt]: https://www.npmjs.com/package/@stdlib/math-base-special-sqrt
[@stdlib/constants/float64/eps]: https://www.npmjs.com/package/@stdlib/constants/tree/main/float64/eps