add numerical recipes library

lib/nr/cpp/recipes/df1dim.cpp

@@ -0,0 +1,19 @@
+#include "nr.h"
+
+extern int ncom;
+extern DP (*nrfunc)(Vec_I_DP &);
+extern void (*nrdfun)(Vec_I_DP &, Vec_O_DP &);
+extern Vec_DP *pcom_p,*xicom_p;
+
+DP NR::df1dim(const DP x)
+{
+	int j;
+	DP df1=0.0;
+	Vec_DP xt(ncom),df(ncom);
+
+	Vec_DP &pcom=*pcom_p,&xicom=*xicom_p;
+	for (j=0;j<ncom;j++) xt[j]=pcom[j]+x*xicom[j];
+	nrdfun(xt,df);
+	for (j=0;j<ncom;j++) df1 += df[j]*xicom[j];
+	return df1;
+}