cosmopolitan/dsp/core/vmatmul3.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
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│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
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#include "dsp/core/core.h"

/**
 * Computes V×M.
 *
 * @see matvmul3() for noncommutative corollary
 */
void *vmatmul3(double R[restrict 3], const double V[3], const double M[3][3]) {
  R[0] = V[0] * M[0][0] + V[1] * M[1][0] + V[2] * M[2][0];
  R[1] = V[0] * M[0][1] + V[1] * M[1][1] + V[2] * M[2][1];
  R[2] = V[0] * M[0][2] + V[1] * M[1][2] + V[2] * M[2][2];
  return R;
}