# signbit
> Return a boolean indicating if the sign bit for a [single-precision floating-point number][ieee754] is on (true) or off (false).
## Usage
```javascript
var signbitf = require( '@stdlib/number/float32/base/signbit' );
```
#### signbitf( x )
Returns a `boolean` indicating if the sign bit for a [single-precision floating-point number][ieee754] is on (`true`) or off (`false`).
```javascript
var toFloat32 = require( '@stdlib/number/float64/base/to-float32' );
var bool = signbitf( toFloat32( 4.0 ) );
// returns false
bool = signbitf( toFloat32( -9.14e-34 ) );
// returns true
bool = signbitf( 0.0 );
// returns false
bool = signbitf( -0.0 );
// returns true
```
## Examples
```javascript
var toFloat32 = require( '@stdlib/number/float64/base/to-float32' );
var randu = require( '@stdlib/random/base/randu' );
var signbitf = require( '@stdlib/number/float32/base/signbit' );
var sign;
var x;
var i;
for ( i = 0; i < 100; i++ ) {
x = (randu()*100.0) - 50.0;
x = toFloat32( x );
sign = signbitf( x );
sign = ( sign ) ? 'true' : 'false';
console.log( 'x: %d. signbit: %s.', x, sign );
}
```
[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985