// bend-blas, the JS twins: plain loops, correct and slow, for the
// interpreter and the tests. An Array<F32> is a JS array of numbers.
// A failure is io_fail(code): the runtime's message for a code is not
// this library's, so the code is the contract on this lane.
function bend_fresh(n) {
  let slots = 1;
  while (slots < n) slots *= 2;
  return new Array(slots).fill(0);
}
function bend_copy(src, n) {
  const c = bend_fresh(n);
  for (let i = 0; i < n; i++) c[i] = src[i];
  return c;
}
function bend_short(a, n) {
  return n > 0x7fffffff || a.length < n;
}
function bend_gemm(ta, tb, m, n, k, alpha, a, b, beta, c) {
  const out = bend_copy(c, m * n);
  for (let i = 0; i < m; i++) for (let j = 0; j < n; j++) {
    let acc = 0;
    for (let l = 0; l < k; l++) acc += (ta ? a[l * m + i] : a[i * k + l]) * (tb ? b[j * k + l] : b[l * n + j]);
    out[i * n + j] = alpha * acc + beta * out[i * n + j];
  }
  return out;
}
function lapack_spotrf(n, a) {
  if (bend_short(a, n * n)) return io_fail(2);
  const L = bend_fresh(n * n);
  for (let j = 0; j < n; j++) {
    let s = a[j * n + j];
    for (let k = 0; k < j; k++) s -= L[j * n + k] * L[j * n + k];
    if (!(s > 0)) return io_fail(j + 1);
    L[j * n + j] = Math.sqrt(s);
    for (let i = j + 1; i < n; i++) {
      let t = a[i * n + j];
      for (let k = 0; k < j; k++) t -= L[i * n + k] * L[j * n + k];
      L[i * n + j] = t / L[j * n + j];
    }
  }
  return io_done(L);
}
io_eff(CID(Lapack.spotrf), lapack_spotrf);