utilq.cpp

来自「算断裂的」· C++ 代码 · 共 93 行

// ------------------------------------------------------------------
// util.cpp
//
// This file defines some global functions used by QMG routines.
// ------------------------------------------------------------------
// Author: Stephen A. Vavasis
// Copyright (c) 1999 by Cornell University.  All rights reserved.
// 
// See the accompanying file 'Copyright' for authorship information,
// the terms of the license governing this software, and disclaimers
// concerning this software.
// ------------------------------------------------------------------
// This file is part of the QMG software.  
// Version 2.0 of QMG, release date September 3, 1999.
// ------------------------------------------------------------------



#include<cctype>
#include "qnamesp.h"

namespace QMG {

  
  // ------------------------------------------------------------------
  // QMG::random_real()
  // Marsaglia random number number generator.  If init is 1, restart, else if init
  // is 0 (default), return a random real number in [0,1].
  // See http://www.mathworks.com/publications/newsletter/pdf/Cleve.pdf
  
  Real random_real(int init) {
    static int i;
    static Real z[32];
    static Real b;
    if (init) {
      i = 0;
      for (int j = 0; j < 32; ++j)
        z[j] = sin((double)(1039 * j)) * sin((double)(1039 * j));
      b = 0.0;
      return 0.0;
    }
    else {
      z[i] = z[(i+20)&31] - z[(i+5)&31] - b;
      if (z[i] < 0) {
        z[i] += 1.0;
        b = MACHINE_EPS;
      }
      else {
        b = 0.0;
      }
      Real rval = z[i];
      i = (i + 1) & 31;
      return rval;
    }
  }
   
  // Eat the white characters in an istream

  istream& eatwhite(istream& is) {
    char c;
    for (;;) {
      if (!is.get(c))
        break;
      if (!isspace(c)) {
        is.putback(c);
        break;
      }
    }
    return is;
  }

  // ------------------------------------------------------------------
  // QMG::compare_nocase
  // Compare two strings ignoring case.  
  

  int compare_nocase(const string& s1, const string& s2) {
    string::const_iterator p2 = s2.begin();
    for (string::const_iterator p1 = s1.begin();
    p1 != s1.end();
    ++p1) {
      if (p2 == s2.end())
        return 1;
      if (toupper(*p1) != toupper(*p2))
        return (toupper(*p1) < toupper(*p2)) ? -1 : 1;
      ++p2;
    }
    return (p2 == s2.end())? 0 : -1;
  }
  
  
}