Initial commit from Polytechnique Montreal

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diff --git a/Utilib/src/zeroin.h b/Utilib/src/zeroin.h
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+/*
+freesteam - IAPWS-IF97 steam tables library
+Copyright (C) 2004-2009  John Pye
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+*/
+
+#ifndef FREESTEAM_ZEROIN_H
+#define FREESTEAM_ZEROIN_H
+
+#include "common.h"
+
+/**
+	Any function that you want to solve using the 'zeroin_solve' function
+	needs to conform to this function prototype. Any parameters required
+	internally by the function can be passed in to the function as a pointer
+	to a struct, array, etc, via the void 'user_data' pointer. Your subject
+	function can then cast the pointer to its correct type, and access the
+	necesssary parameter data, for example:
+
+	-- in your main code
+	typedef struct{double param1, param2} MyData;
+	MyData D = {100., 3.141};
+	double myfunc(double x, void *user_data){
+		MyData *D1 = (MyData *)user_data;
+		return x * D1->param1 + D1->param2;
+	}
+	zeroin_solve(&myfunc, &D, ...);
+*/
+typedef double ZeroInSubjectFunction(double, void *user_data);
+
+/**
+	Attempt to solve the function y = f(x) = 0 by varying x between
+	a lower and upper bound, using the Brent algorithm.
+
+	Originally based on brent solver from netlib, then converted to C++ for
+	used in earlier freesteam versions, and now converted back to pure C again.
+	@see brent.shar at http://www.netlib.org/c/
+
+	@param func the function being solved, must be a ZeroInSubjectFunction.
+	@param lowerbound the lower bound of the range in which a root is sought
+	@param upperbound the upper bound of the range in which a root is sought
+	@param tol maximum permissible magnitude of the function at the solved root location
+	@param user_data additional data that will be passed to the subject function func.
+	@param solution (returned) the value of 'x' at the solution
+	@param error (returned) the value of 'y' at the solution.
+	@return 0 on success
+*/
+
+FREESTEAM_DLL char zeroin_solve(ZeroInSubjectFunction *func, void *user_data, double lowerbound, double upperbound, double tol, double *solution, double *error);
+
+#endif
+