REQ: bounded & weighted least squares

 Hi all!,
 I need to solve a linear least squares problem in which the different points
 have specific weights. Also the adjustable coefficients need to be nonnegative.
 Could somebody indicate a routine to solve this?
 I also need to deal with at least 25 adjustable parameters and the same number
 of independent variables.
 A non linear solver it's ok.
 Thanks in advance
 Merry Christmas!!
 	Dr. Rafael R. Pappalardo
 	Dept. of Physical Chemistry, Univ. of Seville (SPAIN)
 	e-mail: rafapa -AatT-