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77 lines
2.4 KiB
77 lines
2.4 KiB
// Compute decimal Archimedes' constant Pi to arbitrary accuracy.
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#include <cln/output.h>
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#include <cln/real.h>
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#include <cln/real_io.h>
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#include <cctype>
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#include <cstdlib>
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#include <cstring>
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#include <sstream>
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using namespace std;
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using namespace cln;
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static void
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usage (ostream &os)
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{
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os << "Usage: pi [digits]\n";
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os << "Compute decimal Archimedes' constant Pi to arbitrary accuracy.\n\n";
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os << " --help display this help and exit\n";
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os << " --version output version information and exit\n";
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os << " --bibliography output recommended readings and exit\n";
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}
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int
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main (int argc, char * argv[])
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{
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long digits = 100;
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if (argc > 1) {
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if (argc == 2 && !strcmp(argv[1],"--help")) {
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usage(cout);
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return 0;
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}
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if (argc == 2 && !strcmp(argv[1],"--version")) {
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cout << "pi (cln) " << CL_VERSION_MAJOR << "." << CL_VERSION_MINOR << endl;
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cout << "Written by Bruno Haible." << endl;
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cout << endl;
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cout << "Copyright (C) 1998-2007 Bruno Haible, 2000-2007 Richard B. Kreckel." << endl;
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cout << "This is free software; see the source for copying conditions. There is NO" << endl;
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cout << "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE." << endl;
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cout << endl;
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return 0;
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}
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if (argc == 2 && !strcmp(argv[1],"--bibliography")) {
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cout << "Recommended readings:\n";
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cout << "\"Pi\", by Joerg Arndt and Christoph Haenel (1999)\n";
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cout << "\"Pi: A Source Book\" by Lennart Berggren, Jonathan Borwein, Peter Borwein (1997)" << endl;
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return 0;
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}
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if (argc == 2 && isdigit(argv[1][0])) {
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digits = atol(argv[1]);
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} else {
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usage(cerr);
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return 1;
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}
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}
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if (digits) {
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cl_F p = pi(float_format(digits));
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// make CLN believe this number has default_float_format to suppress
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// exponent marker which would be quite boring for 3.1416...
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cl_print_flags cpf;
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cpf.default_float_format = float_format(p);
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// We cannot print directly because people get dazed and confused
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// when they see gratuitous digits (Debian Bug #286266.) And we
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// must not "fix" the output routine because print-read consistency
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// is at stake. As a workaround, print into a buffer so we can chop
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// off characters from its end.
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stringstream buf;
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print_real(buf, cpf, p);
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istreambuf_iterator<char> i = buf.rdbuf();
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while (--digits+2>0)
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cout << *(i++);
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}
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cout << endl;
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return 0;
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}
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