itpp
base
math
log_exp.cpp
Go to the documentation of this file.
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29
#include <
itpp/base/math/log_exp.h
>
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#include <
itpp/base/itcompat.h
>
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namespace
itpp
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{
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// log-2 of the elements
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vec
log2
(
const
vec &x) {
return
apply_function<double>(::
log2
, x); }
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mat
log2
(
const
mat &x) {
return
apply_function<double>(::
log2
, x); }
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// Safe substitute for <tt>log(exp(log_a) + exp(log_b))</tt>
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double
log_add
(
double
log_a,
double
log_b)
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{
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if
(log_a < log_b) {
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double
tmp = log_a;
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log_a = log_b;
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log_b = tmp;
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}
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double
negdelta = log_b - log_a;
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if
((negdelta <
log_double_min
) || std::isnan(negdelta))
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return
log_a;
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else
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return
(log_a + log1p(
std::exp
(negdelta)));
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}
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}
itcompat.h
IT++ compatibility types and functions.
itpp
itpp namespace
Definition:
itmex.h:37
itpp::log_add
double log_add(double log_a, double log_b)
Safe substitute for log(exp(log_a) + exp(log_b))
Definition:
log_exp.cpp:40
itpp::exp
vec exp(const vec &x)
Exp of the elements of a vector x.
Definition:
log_exp.h:155
itpp::log2
vec log2(const vec &x)
log-2 of the elements
Definition:
log_exp.cpp:36
log_exp.h
Logarithmic and exponenential functions - header file.
itpp::log_double_min
const double log_double_min
Constant definition to speed up trunc_log(), trunc_exp() and log_add()
Definition:
log_exp.h:101
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