logarithm to the base of 2 (binary logarithm), base 10 and base n

[bplus]

As I see, QB64 only knows the logarithm function LOG() to the base e.
The following small program calculates the binary logarithm ( logarithm to the base of 2) and the logarithms to the base 10 and n

Code: (Select All)

DIM AS _FLOAT a, n

a = 22

PRINT log2##(a)

PRINT logn##(22, 2)

PRINT logn##(22, 10)

PRINT log10##(22)



'Function log2: logarithm to the base of 2 (binary logarithm)

FUNCTION log2## (a)

    log2## = (LOG(a) / LOG(2))

END FUNCTION



'Function log10: logarithm of a to the base of n

FUNCTION log10## (a)

    log10## = (log2##(a) / log2##(10))

END FUNCTION



'Function logn: logarithm of a to the base of n

FUNCTION logn## (a, n)

    logn## = (log2##(a) / log2(n))

END FUNCTION

LOG10 is often called LG and
LOG is often LN (for natural logarithm).

Could these functions be implemented as standard QB64PE functions: _LOG2(), _LOG10(), LOGn(,)?

Wouldn't it be more efficient to do all other log bases like you did Log2 as it is one less call to User Defined Function. ie 0 calls to user defined function
BaseNLog##(BaseN, a) = Log(a)/Log(BaseN) ' which includes Log2(a)'s which I think is in wiki already