/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+ Copyright (C) 2004-2022 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
bool is_greater(int64_t a, int64_t b)
{ return b * average > a * PERIOD * RESOLUTION ; }
+ int64_t value()
+ { return average / (PERIOD * RESOLUTION); }
+
private :
static constexpr int64_t PERIOD = 4096;
static constexpr int64_t RESOLUTION = 1024;
/// sigmoid(t, x0, y0, C, P, Q) implements a sigmoid-like function using only integers,
/// with the following properties:
-///
+///
/// - sigmoid is centered in (x0, y0)
/// - sigmoid has amplitude [-P/Q , P/Q] instead of [-1 , +1]
/// - limit is (y0 - P/Q) when t tends to -infinity
/// - the slope can be adjusted using C > 0, smaller C giving a steeper sigmoid
/// - the slope of the sigmoid when t = x0 is P/(Q*C)
/// - sigmoid is increasing with t when P > 0 and Q > 0
-/// - to get a decreasing sigmoid, call with -t, or change sign of P
+/// - to get a decreasing sigmoid, change sign of P
/// - mean value of the sigmoid is y0
///
/// Use <https://www.desmos.com/calculator/jhh83sqq92> to draw the sigmoid
int64_t Q)
{
assert(C > 0);
+ assert(Q != 0);
return y0 + P * (t-x0) / (Q * (std::abs(t-x0) + C)) ;
}