restructure and add ipi texs

ws2019/ipi/uebungen/cpp_headers/newton.cc

@@ -0,0 +1,21 @@
+#include "fcpp.hh"
+
+bool gut_genug (double xn, double a) {
+  return fabs(xn*xn-a)<=1E-15;
+}
+
+double wurzelIter (double xn, double a) {
+  return cond( gut_genug(xn,a),
+	       xn,
+	       wurzelIter(0.5*(xn+a/xn),a) );
+}
+
+double wurzel (double a)
+{
+  return wurzelIter(1.0,a);
+}
+
+int main (int argc, char** argv)
+{
+  return print(wurzel(readarg_double(argc,argv,1)));
+}