The largest power of two not greater than n. Returns 0 for n==0, and returns -prevpow2(-n) for negative arguments.


  1. Find the largest power of two not greater than a number:

    julia> prevpow2(10)

    In this example, prevpow2(10) returns the largest power of two that is not greater than 10, which is 8.

  2. Handle zero input:

    julia> prevpow2(0)

    When the input is 0, the function returns 0.

  3. Handle negative input:
    julia> prevpow2(-12)

    For negative inputs, the function returns -prevpow2(-n), where n is the absolute value of the input. In this example, prevpow2(-12) returns -16.

Common mistake example:

julia> prevpow2(1.5)
ERROR: MethodError: no method matching prevpow2(::Float64)

In this example, the input is a floating-point number, which is not supported by the prevpow2 function. It only works with integer inputs. Make sure to provide integer values to the prevpow2 function to avoid such errors.

See Also

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