Physlib

QuantumInfo.ClassicalInfo.ForMathlib.Analysis.SpecialFunctions.Log.NegMulLog

3 declarations

theorem

−xlog⁡x-x \log x is strictly increasing on [0,e−1][0, e^{-1}]

The function f(x)=−xlog⁡xf(x) = -x \log x is strictly monotonically increasing on the closed interval [0,e−1][0, e^{-1}].

theorem

−xlog⁡x-x \log x is strictly decreasing on [e−1,∞)[e^{-1}, \infty)

The function f(x)=−xlog⁡xf(x) = -x \log x (with f(0)=0f(0)=0) is strictly decreasing on the interval [e−1,∞)[e^{-1}, \infty). Here, exp⁡(−1)\exp(-1) denotes the value e−1e^{-1}, and `Set.Ici` denotes the left-closed infinite interval starting from that point.

theorem

−xlog⁡x≤e−1-x \log x \le e^{-1} for x≥0x \ge 0

For any real number x≥0x \ge 0, the function −xlog⁡x-x \log x (denoted as `negMulLog x`) satisfies the inequality −xlog⁡x≤e−1-x \log x \le e^{-1}.