Conversion

`ndarray` (a) / ndarray (a, complex) — Function

Convert a Maxima matrix or list to an ndarray.

If a is a Maxima matrix, it is converted element-by-element into a double-float ndarray with column-major layout. If a is a Maxima list, it creates a 1D ndarray unless a shape argument is provided. Pass complex as the last argument to create a complex-double-float array.

If a is already an ndarray, it is returned unchanged.

Calling forms:

ndarray(matrix) – convert a Maxima matrix to a 2D ndarray
ndarray(matrix, complex) – convert to a complex 2D ndarray
ndarray(list) – convert a flat Maxima list to a 1D ndarray
ndarray(list, shape) – convert a list and reshape to the given dimensions
ndarray(list, shape, complex) – convert a list to a complex ndarray with shape

The shape argument is a Maxima list of dimensions, e.g. [2, 3]. The total number of elements in the list must match the product of the dimensions.

Elements are filled in row-major order from the list, matching the convention that ndarray([1,2,3,4], [2,2]) produces a matrix with first row [1, 2] and second row [3, 4].

Examples

(%i1) load("numerics")$
(%i2) A : ndarray(matrix([1, 2], [3, 4]));
(%o2)            ndarray([2, 2], DOUBLE-FLOAT)
(%i3) np_ref(A, 0, 0);
(%o3)                          1.0
(%i4) B : ndarray([1, 2, 3, 4, 5, 6], [2, 3]);
(%o4)            ndarray([2, 3], DOUBLE-FLOAT)
(%i5) np_shape(B);
(%o5)                        [2, 3]
(%i6) C : ndarray([10, 20, 30]);
(%o6)            ndarray([3], DOUBLE-FLOAT)
(%i7) D : ndarray(matrix([1+%i, 2-3*%i], [4, 5+%i]), complex);
(%o7)            ndarray([2, 2], COMPLEX-DOUBLE-FLOAT)

See also: np_to_matrix, np_to_list, ndarray_p

`ndarray_p` (x) — Function

Test whether x is an ndarray.

Returns true if x is an ndarray handle, false otherwise.

Examples

(%i1) ndarray_p(np_zeros([2, 2]));
(%o1)                         true
(%i2) ndarray_p(42);
(%o2)                        false
(%i3) ndarray_p(matrix([1, 2]));
(%o3)                        false

`np_to_matrix` (a) — Function

Convert a 2D ndarray back to a Maxima matrix.

The ndarray must be 2-dimensional. For 1D ndarrays, use np_to_list instead, or reshape to 2D first with np_reshape. Complex elements are returned in Maxima form (a + b*%i).

Examples

(%i1) A : ndarray(matrix([1, 2], [3, 4]));
(%o1)            ndarray([2, 2], DOUBLE-FLOAT)
(%i2) np_to_matrix(A);
(%o2)         matrix([1.0, 2.0], [3.0, 4.0])
(%i3) B : np_eye(3);
(%o3)            ndarray([3, 3], DOUBLE-FLOAT)
(%i4) np_to_matrix(B);
(%o4)  matrix([1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0])

See also: ndarray, np_to_list, np_reshape

`np_to_list` (a) — Function

Flatten an ndarray to a Maxima list.

Returns all elements as a flat Maxima list in row-major order (rows first, matching NumPy convention). Works for ndarrays of any dimensionality. Complex elements are returned in Maxima form (a + b*%i).

Round-tripping is consistent: ndarray(list, shape) fills in row-major order, and np_to_list returns elements in row-major order.

Examples

(%i1) A : np_arange(4);
(%o1)            ndarray([4], DOUBLE-FLOAT)
(%i2) np_to_list(A);
(%o2)              [0.0, 1.0, 2.0, 3.0]
(%i3) B : ndarray(matrix([1, 2], [3, 4]));
(%o3)            ndarray([2, 2], DOUBLE-FLOAT)
(%i4) np_to_list(B);
(%o4)              [1.0, 2.0, 3.0, 4.0]

See also: ndarray, np_to_matrix, np_flatten

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