Routine Name:   findsolvefield

Description:    Returns a string giving the array location of a particular
                element field value in the hines solver.  Used for
                input/output of values when the original element has been
                taken over by the hines solver and its fields may not be
                updated.

Usage:          findsolvefield hsolve element field

                hsolve      name of the hsolve element
                element     name of an element which was taken over by hsolve
                field       the field of the element whiich is to be accessed

Example:	// statements to create the hsolve element "/cell"
                ...
                setfield /cell chanmode 4
                call /cell SETUP
                ...
                create disk_out /output
                addmsg /cell /output OUTPUT \
                    {findsolvefield /cell /cell/soma/Na Gk}
                ...
                reset
or:
        genesis > echo {findsolvefield /cell /cell/soma/Na Gk}
        givals[108]
        genesis > echo {getfield /cell {findsolvefield /cell /cell/soma/Na Gk}}
        2.634178326e-10

Notes:          When using chanmodes 2 through 5 with the hines solver
                (hsolve), you can no longer assume that all the fields of the
                elements that are taken over by hsolve will be updated.  The
                findsolvefield function is used to access the hsolve arrays
                directly to output field values instead of having to use the
                old disabled elements.  This allows one to establish new
                messages for the output of field values after setup of the
                hsolve element.  The example above shows how to output the Gk
                field of the Na channel from the hsolve element /cell.  Note
                that the fields Gk, Ik, Ek, and Im are not available for
                chanmodes 2 and 3, and require the use of findsolvefield
                in chanmodes 4 and 5.

See also:       hsolve
