1 // Compute decimal Archimedes' constant Pi to arbitrary accuracy.
2
3 #include <cln/output.h>
4 #include <cln/real.h>
5 #include <cln/real_io.h>
6 #include <cln/version.h>
7 #include <cctype>
8 #include <cstdlib>
9 #include <cstring>
10 #include <sstream>
11
12 using namespace std;
13 using namespace cln;
14
15 static void
usage(ostream & os)16 usage (ostream &os)
17 {
18 os << "Usage: pi [digits]\n";
19 os << "Compute decimal Archimedes' constant Pi to arbitrary accuracy.\n\n";
20 os << " --help display this help and exit\n";
21 os << " --version output version information and exit\n";
22 os << " --bibliography output recommended readings and exit\n";
23 }
24
25 int
main(int argc,char * argv[])26 main (int argc, char * argv[])
27 {
28 long digits = 100;
29 if (argc > 1) {
30 if (argc == 2 && !strcmp(argv[1],"--help")) {
31 usage(cout);
32 return 0;
33 }
34 if (argc == 2 && !strcmp(argv[1],"--version")) {
35 cout << "pi (CLN "
36 << version_major << "." << version_minor << "." << version_patchlevel
37 << ")" << endl;
38 cout << "Written by Bruno Haible and Richard B. Kreckel." << endl;
39 cout << endl;
40 cout << "Copyright (C) 1988-2008 Bruno Haible, 2000-2009 Richard B. Kreckel." << endl;
41 cout << "This is free software; see the source for copying conditions. There is NO" << endl;
42 cout << "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE." << endl;
43 cout << endl;
44 return 0;
45 }
46 if (argc == 2 && !strcmp(argv[1],"--bibliography")) {
47 cout << "Recommended readings:\n";
48 cout << "\"Pi\", by Joerg Arndt and Christoph Haenel (1999)\n";
49 cout << "\"Pi: A Source Book\" by Lennart Berggren, Jonathan Borwein, Peter Borwein (1997)" << endl;
50 return 0;
51 }
52 if (argc == 2 && isdigit(argv[1][0])) {
53 digits = atol(argv[1]);
54 } else {
55 usage(cerr);
56 return 1;
57 }
58 }
59
60 if (digits) {
61 cl_F p = pi(float_format(digits));
62 // make CLN believe this number has default_float_format to suppress
63 // exponent marker which would be quite boring for 3.1416...
64 cl_print_flags cpf;
65 cpf.default_float_format = float_format(p);
66 // We cannot print directly because people get dazed and confused
67 // when they see gratuitous digits (Debian Bug #286266.) And we
68 // must not "fix" the output routine because print-read consistency
69 // is at stake. As a workaround, print into a buffer so we can chop
70 // off characters from its end.
71 stringstream buf;
72 print_real(buf, cpf, p);
73 istreambuf_iterator<char> i = buf.rdbuf();
74 while (--digits+2>0)
75 cout << *(i++);
76 }
77 cout << endl;
78
79 return 0;
80 }
81