math.h

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/*
 * CDDL HEADER START
 *
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2023 Saso Kiselkov. All rights reserved.
 */
#ifndef _ACF_UTILS_MATH_H_
#define _ACF_UTILS_MATH_H_
 
#include "assert.h"
#include "math_core.h"
#include "geom.h"
 
#ifdef  __cplusplus
extern "C" {
#endif
 
#define POW4(x) ((x) * (x) * (x) * (x))
#define POW3(x) ((x) * (x) * (x))
#define POW2(x) ((x) * (x))
#ifndef ABS
#define ABS(x)  ((x) > 0 ? (x) : -(x))
#endif
 
struct vect2_s;
 
API_EXPORT unsigned quadratic_solve(double a, double b, double c, double x[2]);
API_EXPORT double fx_lin(double x, double x1, double y1, double x2, double y2)
    PURE_ATTR;
API_EXPORT double fx_lin_multi(double x, const struct vect2_s *points,
    bool_t extrapolate) PURE_ATTR;
API_EXPORT double fx_lin_multi2(double x, const struct vect2_s *points,
    size_t n_points, bool_t extrapolate) PURE_ATTR;
API_EXPORT double *fx_lin_multi_inv(double y, const struct vect2_s *points,
    size_t *num_out);
API_EXPORT double *fx_lin_multi_inv2(double y, const struct vect2_s *points,
    bool_t extrapolate, size_t *num_out);
API_EXPORT double *fx_lin_multi_inv3(double y, const struct vect2_s *points,
    size_t n_points, bool_t extrapolate, size_t *num_out);
 
static inline double
wavg_impl(double x, double y, double w, const char *file, int line)
{
    LACF_UNUSED(file);
    LACF_UNUSED(line);
    ASSERT_MSG(!isnan(w), "%f is NAN: called from: %s:%d", w, file, line);
    ASSERT_MSG(w >= 0.0, "%f < 0.0: called from: %s:%d", w, file, line);
    ASSERT_MSG(w <= 1.0, "%f > 1.0: called from: %s:%d", w, file, line);
    return (x + (y - x) * w);
}
#define wavg(x, y, w)   wavg_impl((x), (y), (w), __FILE__, __LINE__)
 
static inline double
wavg2(double x, double y, double w)
{
    return (x + (y - x) * w);
}
 
static inline double
iter_fract(double x, double min_val, double max_val, bool_t clamp_output)
{
    ASSERT3F(min_val, !=, max_val);
    x = (x - min_val) / (max_val - min_val);
    if (clamp_output)
        x = clamp(x, 0, 1);
    return (x);
}
 
#define MAX_PN_INTERP_ORDER 64
typedef struct {
    unsigned    order;
    double      coeff[MAX_PN_INTERP_ORDER];
} pn_interp_t;
 
API_EXPORT void pn_interp_init(pn_interp_t *interp, const vect2_t *points,
    unsigned npts);
 
static inline double
pn_interp_run(double x, const pn_interp_t *interp)
{
    double y = 0, power = 1;
 
    ASSERT(interp != NULL);
    ASSERT(interp->order != 0);
    for (unsigned i = 0; i < interp->order; i++) {
        y += interp->coeff[i] * power;
        power *= x;
    }
 
    return (y);
}
 
static inline double
smoothstep(double x, double edge0, double edge1)
{
    ASSERT(!isnan(x));
    ASSERT3F(edge1, >, edge0);
    x = clamp((x - edge0) / (edge1 - edge0), 0, 1);
    return (POW2(x) * (3 - 2 * x));
}
 
static inline double
smoothstep_inv(double x)
{
    ASSERT(!isnan(x));
    return (0.5 - sin(asin(1 - 2 * x) / 3));
}
 
#define HROUND2(oldval, newval, step, hyst_rng) \
    do { \
        double tmpval = round((newval) / (step)) * (step); \
        if (isnan((oldval))) { \
            (oldval) = tmpval; \
        } else if ( \
            (newval) > (oldval) + (step) * (0.5 + (hyst_rng)) || \
            (newval) < (oldval) - (step) * (0.5 + (hyst_rng))) { \
            (oldval) = tmpval; \
        } \
    } while (0)
 
#define HROUND(oldval, newval, step) \
    HROUND2((oldval), (newval), (step), 0.35)
 
#ifdef  __cplusplus
}
#endif
 
#endif  /* _ACF_UTILS_GEOM_H_ */