Computes the inverse of `rfftn`. This function computes the inverse of the N-dimensional discrete Fourier Transform for real input over any number of axes in an M-dimensional array by means of the Fast Fourier Transform (FFT). In other words, ``irfftn(rfftn(a), a.shape) == a``
(a, s=None, axes=None, norm=None, out=None)
| 1472 | |
| 1473 | @array_function_dispatch(_fftn_dispatcher) |
| 1474 | def irfftn(a, s=None, axes=None, norm=None, out=None): |
| 1475 | """ |
| 1476 | Computes the inverse of `rfftn`. |
| 1477 | |
| 1478 | This function computes the inverse of the N-dimensional discrete |
| 1479 | Fourier Transform for real input over any number of axes in an |
| 1480 | M-dimensional array by means of the Fast Fourier Transform (FFT). In |
| 1481 | other words, ``irfftn(rfftn(a), a.shape) == a`` to within numerical |
| 1482 | accuracy. (The ``a.shape`` is necessary like ``len(a)`` is for `irfft`, |
| 1483 | and for the same reason.) |
| 1484 | |
| 1485 | The input should be ordered in the same way as is returned by `rfftn`, |
| 1486 | i.e. as for `irfft` for the final transformation axis, and as for `ifftn` |
| 1487 | along all the other axes. |
| 1488 | |
| 1489 | Parameters |
| 1490 | ---------- |
| 1491 | a : array_like |
| 1492 | Input array. |
| 1493 | s : sequence of ints, optional |
| 1494 | Shape (length of each transformed axis) of the output |
| 1495 | (``s[0]`` refers to axis 0, ``s[1]`` to axis 1, etc.). `s` is also the |
| 1496 | number of input points used along this axis, except for the last axis, |
| 1497 | where ``s[-1]//2+1`` points of the input are used. |
| 1498 | Along any axis, if the shape indicated by `s` is smaller than that of |
| 1499 | the input, the input is cropped. If it is larger, the input is padded |
| 1500 | with zeros. |
| 1501 | |
| 1502 | .. versionchanged:: 2.0 |
| 1503 | |
| 1504 | If it is ``-1``, the whole input is used (no padding/trimming). |
| 1505 | |
| 1506 | If `s` is not given, the shape of the input along the axes |
| 1507 | specified by axes is used. Except for the last axis which is taken to |
| 1508 | be ``2*(m-1)`` where ``m`` is the length of the input along that axis. |
| 1509 | |
| 1510 | .. deprecated:: 2.0 |
| 1511 | |
| 1512 | If `s` is not ``None``, `axes` must not be ``None`` either. |
| 1513 | |
| 1514 | .. deprecated:: 2.0 |
| 1515 | |
| 1516 | `s` must contain only ``int`` s, not ``None`` values. ``None`` |
| 1517 | values currently mean that the default value for ``n`` is used |
| 1518 | in the corresponding 1-D transform, but this behaviour is |
| 1519 | deprecated. |
| 1520 | |
| 1521 | axes : sequence of ints, optional |
| 1522 | Axes over which to compute the inverse FFT. If not given, the last |
| 1523 | `len(s)` axes are used, or all axes if `s` is also not specified. |
| 1524 | Repeated indices in `axes` means that the inverse transform over that |
| 1525 | axis is performed multiple times. |
| 1526 | |
| 1527 | .. deprecated:: 2.0 |
| 1528 | |
| 1529 | If `s` is specified, the corresponding `axes` to be transformed |
| 1530 | must be explicitly specified too. |
| 1531 |
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