stats.c

#include <math.h>
#include <lcthw/stats.h>
#include <stdlib.h>
#include <lcthw/dbg.h>

Stats *Stats_recreate(double sum, double sumsq, unsigned long n,
        double min, double max)
{
    Stats *st = malloc(sizeof(Stats));
    check_mem(st);

    st->sum = sum;
    st->sumsq = sumsq;
    st->n = n;
    st->min = min;
    st->max = max;

    return st;

error:
    return NULL;
}

Stats *Stats_create()
{
    return Stats_recreate(0.0, 0.0, 0L, 0.0, 0.0);
}

double Stats_mean(Stats * st)
{
    return st->sum / st->n;
}

double Stats_stddev(Stats * st)
{
    return sqrt((st->sumsq - (st->sum * st->sum / st->n)) /
            (st->n - 1));
}

void Stats_sample(Stats * st, double s)
{
    st->sum += s;
    st->sumsq += s * s;

    if (st->n == 0) {
        st->min = s;
        st->max = s;
    } else {
        if (st->min > s)
            st->min = s;
        if (st->max < s)
            st->max = s;
    }

    st->n += 1;
}

void Stats_dump(Stats * st)
{
    fprintf(stderr,
            "sum: %f, sumsq: %f, n: %ld, "
            "min: %f, max: %f, mean: %f, stddev: %f",
            st->sum, st->sumsq, st->n, st->min, st->max, Stats_mean(st),
            Stats_stddev(st));
}