add numerical recipes library

lib/nr/k_and_r/recipes/hpsel.c

@@ -0,0 +1,29 @@
+
+void hpsel(m,n,arr,heap)
+float arr[],heap[];
+unsigned long m,n;
+{
+	void sort();
+	void nrerror();
+	unsigned long i,j,k;
+	float swap;
+
+	if (m > n/2 || m < 1) nrerror("probable misuse of hpsel");
+	for (i=1;i<=m;i++) heap[i]=arr[i];
+	sort(m,heap);
+	for (i=m+1;i<=n;i++) {
+		if (arr[i] > heap[1]) {
+			heap[1]=arr[i];
+			for (j=1;;) {
+				k=j << 1;
+				if (k > m) break;
+				if (k != m && heap[k] > heap[k+1]) k++;
+				if (heap[j] <= heap[k]) break;
+				swap=heap[k];
+				heap[k]=heap[j];
+				heap[j]=swap;
+				j=k;
+			}
+		}
+	}
+}