function isNaN_(x) {
	  var $x = convertToTensor(x, 'x', 'isNaN');
	  var inputs = {
	    x: $x
	  };
	  return ENGINE.runKernel(IsNan, inputs);
	}
RReturns which elements of x are NaN.

```js
const x = tf.tensor1d([NaN, Infinity, -Infinity, 0, 1]);

x.isNaN().print();  // or tf.isNaN(x)
```
@param x The input Tensor.

@doc {heading: 'Operations', subheading: 'Basic math'}