1 files changed, 66 insertions, 0 deletions
diff --git a/math/nlfit/nlinit.gx b/math/nlfit/nlinit.gx
new file mode 100644
index 00000000..be6e436a
--- /dev/null
+++ b/math/nlfit/nlinit.gx
@@ -0,0 +1,66 @@
+$if (datatype == r)
+include "nlfitdefr.h"
+$else
+include "nlfitdefd.h"
+$endif
+
+# NLINIT --  Initialize for non-linear fitting
+
+procedure nlinit$t (nl, fnc, dfnc, params, dparams, nparams, plist, nfparams,
+		    tol, itmax)
+
+pointer	nl		# pointer to nl fitting structure
+int	fnc		# fitting function address
+int	dfnc		# derivative function address
+PIXEL	params[ARB]	# initial values for the parameters
+PIXEL	dparams[ARB]	# initial guess at uncertainties in parameters
+int	nparams		# number of parameters
+int	plist[ARB]	# list of active parameters
+int	nfparams	# number of fitted parameters
+PIXEL	tol		# fitting tolerance
+int	itmax		# maximum number of iterations
+
+errchk	malloc, calloc, nl_list
+
+begin
+	# Allocate space for the non-linear package structure.
+	call calloc (nl, LEN_NLSTRUCT, TY_STRUCT)
+
+	# Store the addresses of the non-linear functions.
+	NL_FUNC(nl) = fnc
+	NL_DFUNC(nl) = dfnc
+
+	# Allocate temporary space for arrays.
+	call calloc (NL_ALPHA(nl), nfparams * nfparams, TY_PIXEL)
+	call calloc (NL_COVAR(nl), nfparams * nfparams, TY_PIXEL)
+	call calloc (NL_CHOFAC(nl), nfparams * nfparams, TY_PIXEL)
+	call calloc (NL_BETA(nl), nfparams, TY_PIXEL)
+
+	# Allocate space for parameter and trial parameter vectors.
+	call calloc (NL_DERIV(nl), nparams, TY_PIXEL)
+	call calloc (NL_PARAM(nl), nparams, TY_PIXEL)
+	call calloc (NL_OPARAM(nl), nparams, TY_PIXEL)
+	call calloc (NL_TRY(nl), nparams, TY_PIXEL)
+	call calloc (NL_DPARAM(nl), nparams, TY_PIXEL)
+	call calloc (NL_DELPARAM(nl), nparams, TY_PIXEL)
+	call calloc (NL_PLIST(nl), nparams, TY_INT)
+
+	# Initialize the parameters.
+	NL_NPARAMS(nl) = nparams
+	NL_NFPARAMS(nl) = nfparams
+	call amov$t (params, PARAM(NL_PARAM(nl)), nparams)
+	call amov$t (params, PARAM(NL_OPARAM(nl)), nparams)
+	call amov$t (dparams, DPARAM(NL_DELPARAM(nl)), nparams)
+	call amovi (plist, PLIST(NL_PLIST(nl)), nfparams)
+	NL_TOL(nl) = tol
+	NL_ITMAX(nl) = itmax
+	NL_SCATTER(nl) = PIXEL(0.0)
+
+	# Set up the parameter list.
+	iferr {
+	    call nl_list (PLIST(NL_PLIST(nl)), NL_NPARAMS(nl), NL_NFPARAMS(nl))
+	} then {
+	    call nlfree$t (nl)
+	    nl = NULL
+	}
+end