43 lines
847 B
C
43 lines
847 B
C
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/* -*- mode: C; c-basic-offset: 2; indent-tabs-mode: nil; -*- */
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#include <math.h>
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#include "variable.h"
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void
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variable_init (Variable *variable)
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{
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variable->weight = 0.0;
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variable->sum = 0.0;
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variable->sum2 = 0.0;
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}
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void
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variable_add_weighted (Variable *variable,
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double value,
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double weight)
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{
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variable->weight += weight;
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variable->sum += weight * value;
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variable->sum2 += weight * value * value;
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}
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void
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variable_add (Variable *variable,
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double value)
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{
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variable_add_weighted (variable, value, 1.);
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}
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double
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variable_mean (Variable *variable)
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{
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return variable->sum / variable->weight;
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}
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double
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variable_standard_deviation (Variable *variable)
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{
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double mean = variable_mean (variable);
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return sqrt (variable->sum2 / variable->weight - mean * mean);
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}
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