## 3.105. __nv_fast_log2f

Prototype:

```float @__nv_fast_log2f(float %x)

```

Description:

Calculate the fast approximate base 2 logarithm of the input argument x.

Returns:

Returns an approximation to ${\mathrm{log}}_{2}\left(x\right)$ .

Note:

For accuracy information for this function see the CUDA C Programming Guide, Appendix D.2, Table 9.

Input and output in the denormal range is flushed to sign preserving 0.0.

Library Availability:

Compute 2.0: Yes

Compute 3.0: Yes

Compute 3.5: Yes