pro d17_he3fit,win,pin,pout,yout,PFIX=pfix,LIMITS=lims,DSEL=dsel,CROSS=cross

                LAMP procedure to fit the 3He data to calculate the

                polarization decay constants.

NECESSARY INPUT:

                win=the workspace with the values of phi.

                                calculated using aw_he3calibrate

                pin=the input parameters:

                                pin(0) = definition of time t=0 (by 'julday')

                                pin(1) = initial polarization of the He3 gas       (%)

                                pin(2) = the time constant for decay                                 (hours)

                                pin(3) = the inefficiency of the polarizer

                                pin(4) = the pressure of the gas                         (bar)

                                pin(5) = the wavelength                                      (Angstrom)

OPTIONAL INPUT

                pfix=a 6-element array showing which of pin are fixed and which are free

                                A value of zero is free, a value of one is fixed

                limits=a 2 column by 6 row array with the upper and lower limits

                                for each parameter.  Set values to -1 for no limit

                dsel=a 2row array with the same number of columns as data points

                               This parameter can be set to deselect data points

                               The top row refers to polarization data, while the bottom refers to the transmission

                               A value of 0 means that the corresponding data point is DESELECTED

                               Any other value and the point is SELECTED.

                               Default is (of course) all data points selected

                cross=0 if the 3He is polarized in the SAME direction as the monochromator

                        =1 if the 3He is polarized OPPOSITE to the monochromator

                                Default is cross=0

OUTPUT:

                pout=the output parameters with errors as a 2 column array:

                                pout(0) = definition of time t=0 (by 'julday')

                                pout(1) = initial polarization of the He3 gas     (%)

                                pout(2) = the time constant for decay                              (hours)

                                pout(3) = the inefficiency of the polarizer

                                pout(4) = the pressure of the gas                      (bar)

                                pout(5) = the wavelength                                   (Angstrom)

                                pout(6) = the first flipper efficiency

                                pout(7) = the second flipper efficiency

                yout=the values of phi and trans as a function of time

                Example:

                d17_he3fit,w2,[julday(8,3,2004,14,15,00),0.6,150,0.013,0.6,5.3],pout,w11, $

                                PFIX=[0,0,0,1,0,1], $

                                LIMITS=[[-1,min(x2)],[0.5,0.65],[100,200],[0,0.02],[0.5,0.7],[-1,-1]]