# MiniZinc Documentation - Standard Library

These builtins implement exponential and logarithmic functions.

Functions and Predicates
function float: exp(float: x)

Return $$e ^ {{\bf x}}$$

function var float: exp(var float: x) =
let { var float: r, constraint float_exp(x, r), } in (r)
(standard decomposition from builtins.mzn:393)

Return $$e ^ {{\bf x}}$$

function float: ln(float: x)

Return $$\ln {\bf x}$$

function var float: ln(var float: x) =
let { var float: r, constraint float_ln(x, r), } in (r)
(standard decomposition from builtins.mzn:402)

Return $$\ln {\bf x}$$

function float: log(float: x, float: y)

Return $$\log_{{\bf x}} {\bf y}$$

function float: log10(float: x)

Return $$\log_{10} {\bf x}$$

function var float: log10(var float: x) =
let { var float: r, constraint float_log10(x, r), } in (r)
(standard decomposition from builtins.mzn:411)

Return $$\log_{10} {\bf x}$$

function float: log2(float: x)

Return $$\log_{2} {\bf x}$$

function var float: log2(var float: x) =
let { var float: r, constraint float_log2(x, r), } in (r)
(standard decomposition from builtins.mzn:420)

Return $$\log_{2} {\bf x}$$