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* October 23, 2000 and Feb, 2001.
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4 |
* October 23, 2000 and Feb, 2001.
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*
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*
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* dnbinom_mu(): Martin Maechler, June 2008
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* dnbinom_mu(): Martin Maechler, June 2008
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*
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*
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* Merge in to R:
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* Merge in to R:
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* Copyright (C) 2000--2014, The R Core Team
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* Copyright (C) 2000--2016, The R Core Team
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* (at your option) any later version.
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R_D_nonint_check(x);
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R_D_nonint_check(x);
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if (x < 0 || !R_FINITE(x)) return R_D__0;
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if (x < 0 || !R_FINITE(x)) return R_D__0;
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/* limiting case as size approaches zero is point mass at zero */
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/* limiting case as size approaches zero is point mass at zero */
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if (x == 0 && size==0) return R_D__1;
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if (x == 0 && size==0) return R_D__1;
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x = R_forceint(x);
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x = R_forceint(x);
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if(!R_FINITE(size)) size = DBL_MAX;
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ans = dbinom_raw(size, x+size, prob, 1-prob, give_log);
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ans = dbinom_raw(size, x+size, prob, 1-prob, give_log);
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p = ((double)size)/(size+x);
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p = ((double)size)/(size+x);
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return((give_log) ? log(p) + ans : p * ans);
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return((give_log) ? log(p) + ans : p * ans);
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}
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}
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double dnbinom_mu(double x, double size, double mu, int give_log)
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double dnbinom_mu(double x, double size, double mu, int give_log)
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{
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{
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/* originally, just set prob := size / (size + mu) and called dbinom_raw(),
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/* originally, just set prob := size / (size + mu) and called dbinom_raw(),
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* but that suffers from cancellation when mu << size */
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* but that suffers from cancellation when mu << size */
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double ans, p;
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- |
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64 |
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| 65 |
#ifdef IEEE_754
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#ifdef IEEE_754
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if (ISNAN(x) || ISNAN(size) || ISNAN(mu))
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if (ISNAN(x) || ISNAN(size) || ISNAN(mu))
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return x + size + mu;
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return x + size + mu;
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#endif
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#endif
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| 73 |
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73 |
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/* limiting case as size approaches zero is point mass at zero,
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74 |
/* limiting case as size approaches zero is point mass at zero,
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* even if mu is kept constant. limit distribution does not
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* even if mu is kept constant. limit distribution does not
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* have mean mu, though.
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* have mean mu, though.
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*/
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*/
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if (x == 0 && size==0) return R_D__1;
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if (x == 0 && size == 0) return R_D__1;
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| 79 |
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- |
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| 80 |
x = R_forceint(x);
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79 |
x = R_forceint(x);
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| - |
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if(!R_FINITE(size)) // limit case: Poisson
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| - |
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81 |
return(dpois_raw(x, mu, give_log));
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| - |
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82 |
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| 81 |
if(x == 0)/* be accurate, both for n << mu, and n >> mu :*/
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83 |
if(x == 0)/* be accurate, both for n << mu, and n >> mu :*/
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| 82 |
return R_D_exp(size * (size < mu ? log(size/(size+mu)) : log1p(- mu/(size+mu))));
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84 |
return R_D_exp(size * (size < mu ? log(size/(size+mu)) : log1p(- mu/(size+mu))));
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| 83 |
if(x < 1e-10 * size) { /* don't use dbinom_raw() but MM's formula: */
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85 |
if(x < 1e-10 * size) { /* don't use dbinom_raw() but MM's formula: */
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| 84 |
/* FIXME --- 1e-8 shows problem; rather use algdiv() from ./toms708.c */
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86 |
/* FIXME --- 1e-8 shows problem; rather use algdiv() from ./toms708.c */
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| 85 |
p = (size < mu ? log(size/(1 + size/mu)) : log(mu / (1 + mu/size)));
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87 |
double p = (size < mu ? log(size/(1 + size/mu)) : log(mu / (1 + mu/size)));
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| 86 |
return R_D_exp(x * p - mu - lgamma(x+1) +
|
88 |
return R_D_exp(x * p - mu - lgamma(x+1) +
|
| 87 |
log1p(x*(x-1)/(2*size)));
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89 |
log1p(x*(x-1)/(2*size)));
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| - |
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90 |
} else {
|
| - |
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91 |
/* no unnecessary cancellation inside dbinom_raw, when
|
| - |
|
92 |
* x_ = size and n_ = x+size are so close that n_ - x_ loses accuracy */
|
| - |
|
93 |
double p = ((double)size)/(size+x),
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| - |
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94 |
ans = dbinom_raw(size, x+size, size/(size+mu), mu/(size+mu), give_log);
|
| - |
|
95 |
return((give_log) ? log(p) + ans : p * ans);
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| 88 |
}
|
96 |
}
|
| 89 |
/* else: no unnecessary cancellation inside dbinom_raw, when
|
- |
|
| 90 |
* x_ = size and n_ = x+size are so close that n_ - x_ loses accuracy
|
- |
|
| 91 |
*/
|
- |
|
| 92 |
ans = dbinom_raw(size, x+size, size/(size+mu), mu/(size+mu), give_log);
|
- |
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| 93 |
p = ((double)size)/(size+x);
|
- |
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| 94 |
return((give_log) ? log(p) + ans : p * ans);
|
- |
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| 95 |
}
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97 |
}
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