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127 lines
3.4 KiB
127 lines
3.4 KiB
/*
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* The following program was used to compute the first 100,000,000 decimal
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* digits of e = exp(1), on December 18-20, 1998.
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* Timings on a Sun UltraSparc-II (296 MHz), running Solaris 2.6, equipped
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* with 512 MB RAM and 2 GB swap:
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*
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* 100 digits:
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* computation of e: real time: 0.002 s, run time: 0.000 s
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* conversion to decimal: real time: 0.003 s, run time: 0.000 s
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* 1000 digits:
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* computation of e: real time: 0.018 s, run time: 0.020 s
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* conversion to decimal: real time: 0.028 s, run time: 0.020 s
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* 10000 digits:
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* computation of e: real time: 0.488 s, run time: 0.480 s
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* conversion to decimal: real time: 1.059 s, run time: 1.060 s
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* 100000 digits:
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* computation of e: real time: 8.139 s, run time: 8.010 s
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* conversion to decimal: real time: 16.593 s, run time: 16.540 s
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* 1000000 digits:
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* computation of e: real time: 122.383 s, run time: 121.020 s
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* conversion to decimal: real time: 252.524 s, run time: 250.760 s
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* 10000000 digits:
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* computation of e: real time: 2152.061 s, run time: 2056.430 s
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* conversion to decimal: real time: 3579.670 s, run time: 3388.990 s
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* 100000000 digits:
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* computation of e: real time: 40061.367 s, run time: 30449.630 s
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* conversion to decimal: real time: 54507.003 s, run time: 40063.510 s
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*/
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#include <cln/number.h>
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#include <cln/io.h>
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#include <cln/integer.h>
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#include <cln/integer_io.h>
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#include <cln/float.h>
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#include <cln/float_io.h>
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#include <cln/real.h>
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#include <cln/complex.h>
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#include <string.h>
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#include <cln/timing.h>
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#include <cmath>
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using namespace std;
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using namespace cln;
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void
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sum_exp1 (uintL a, uintL b, cl_I & first, cl_I & second)
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{
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switch (b - a)
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{
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case 1:
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first = second = b;
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break;
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case 2:
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{
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cl_I s = (a + b) >> 1;
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second = s * b;
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first = second + b;
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}
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break;
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default:
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{
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cl_I lp, lq, rp, rq, tmp;
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uintL mid = (a + b) >> 1;
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sum_exp1 (a, mid, lp, lq);
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sum_exp1 (mid, b, rp, rq);
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tmp = lp * rq;
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first = tmp + rp;
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second = lq * rq;
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}
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break;
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}
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}
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namespace cln {
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extern cl_LF cl_I_to_LF(const cl_I&, uintC);
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};
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void
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const_exp1 (cl_LF & result, uintL dec)
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{
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uintL c = (uintL) (dec * ::log (10));
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uintL n = dec;
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uintC actuallen = (uintC)(3.321928094 * dec / intDsize);
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n = (uintL) ((n + c) / ::log ((double)n));
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n = (uintL) ((n + c) / ::log ((double)n));
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n = (uintL) ((n + c) / ::log ((double)n));
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n += 2;
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actuallen += 2;
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cout << "n = " << n << endl;
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cout << "actuallen = " << actuallen << endl;
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cl_I p, q;
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sum_exp1 (0, n, p, q);
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cout << "sum_exp1 ends ok" << endl;
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result = The(cl_LF)(cl_I_to_LF (p, actuallen) / cl_I_to_LF (q, actuallen));
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cout << "const_exp1 returns ok" << endl;
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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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int digits = 100;
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while (argc >= 3) {
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if (!strcmp(argv[1],"-n")) {
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digits = atoi(argv[2]);
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argc -= 2; argv += 2;
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continue;
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}
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break;
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}
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if (argc < 1)
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return(1);
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cl_LF c1;
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long l = digits;
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cout << "\nCalculating exp1 to " << l << " decimals" << endl;
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{ CL_TIMING;
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const_exp1 (c1, l);
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}
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{ CL_TIMING;
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cout << "@" << endl;
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cout << c1 << endl;
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cout << "@" << endl;
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}
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return(0);
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}
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