Function scalbn 

pub fn scalbn<F: Float>(x: F, n: i32) -> F
where
    u32: CastInto<F::Int>,
    F::Int: CastFrom<i32> + CastFrom<u32>,

Scale the exponent.

From N3220:

The scalbn and scalbln functions compute x * b^n, where b = FLT_RADIX if the return type of the function is a standard floating type, or b = 10 if the return type of the function is a decimal floating type. A range error occurs for some finite x, depending on n.

[…]

• scalbn(±0, n) returns ±0.
• scalbn(x, 0) returns x.
• scalbn(±∞, n) returns ±∞.

If the calculation does not overflow or underflow, the returned value is exact and independent of the current rounding direction mode.