add numerical recipes library

lib/nr/cpp/recipes/arcmak.cpp

@@ -0,0 +1,22 @@
+#include <limits>
+#include "nr.h"
+using namespace std;
+
+void NR::arcmak(Vec_I_ULNG &nfreq, unsigned long nchh, unsigned long nradd,
+	arithcode &acode)
+{
+	const unsigned long MAXULNG=numeric_limits<unsigned long>::max();
+	unsigned long j;
+
+	unsigned long MC=acode.ncumfq.size()-2;
+	if (nchh > MC) nrerror("input radix may not exceed MC in arcmak.");
+	if (nradd > 256) nrerror("output radix may not exceed 256 in arcmak.");
+
+	acode.minint=MAXULNG/nradd;
+	acode.nch=nchh;
+	acode.nrad=nradd;
+	acode.ncumfq[0]=0;
+	for (j=1;j<=acode.nch;j++)
+		acode.ncumfq[j]=acode.ncumfq[j-1]+MAX(nfreq[j-1],(unsigned long) 1);
+	acode.ncum=acode.ncumfq[acode.nch+1]=acode.ncumfq[acode.nch]+1;
+}