polyfit method

Float64List polyfit(Float64List x, Float64List y, { CoeffMode mode = CoeffMode.scaled, })

Fits polynomial coefficients to x and y, stores them in this instance, and returns the fitted coefficient vector.

Implementation

Float64List polyfit(
  Float64List x,
  Float64List y, {
  CoeffMode mode = CoeffMode.scaled,
}) {
  if (x.length != y.length) {
    throw ArgumentError('x and y must have the same length');
  }

  final n = x.length;
  _ensureCapacity(n);
  ffi.Pointer<ffi.Double> xPtr = ffi.nullptr;
  ffi.Pointer<ffi.Double> yPtr = ffi.nullptr;
  ffi.Pointer<ffi.Double> coeffPtr = ffi.nullptr;

  try {
    xPtr = calloc<ffi.Double>(n);
    yPtr = calloc<ffi.Double>(n);
    coeffPtr = calloc<ffi.Double>(deg + 1);

    xPtr.asTypedList(n).setAll(0, x);
    yPtr.asTypedList(n).setAll(0, y);

    final rc = yl_polyfit_ctx_fit_f64(
      res.ctx,
      xPtr,
      yPtr,
      n,
      mode.value,
      coeffPtr,
      ffi.nullptr,
    );
    if (rc != 0) {
      throw StateError('yl_polyfit_ctx_fit_f64 failed with code $rc');
    }

    final out = Float64List.fromList(coeffPtr.asTypedList(deg + 1));
    _coeffs = out;
    _coeffMode = mode;
    return Float64List.fromList(out);
  } finally {
    if (xPtr != ffi.nullptr) calloc.free(xPtr);
    if (yPtr != ffi.nullptr) calloc.free(yPtr);
    if (coeffPtr != ffi.nullptr) calloc.free(coeffPtr);
  }
}