lisp - Is there a high-precision logarithm calculator in elisp? -

in class, final project, working on improving algorithm matches prefix power of 2

(i.e. input="25", output="2^8=256", input="99", output="2^99=9903520314283042199192993792...")

anyways, relying on logarithms identify matching prefixes. logarithm precision matter , looking better log functions. standard log function , calc-function both have same precision. there options if wanted better precision?

based off several google searches, i've come conclusion 1 not exist. if inform me otherwise, happily change best answer however.