indices(spec)

Create multiple index varaibles at once.

Parameters:

Name	Type	Description	Default
spec	int or str	If int, indicate the number of 'anonymous' index variables to create. These anonymous variables will be numbered sequentially starting from 0, and are guaranteed to be unique within runtime. If str, must be a comma/space-delimited list of symbols in the format as described in funfact.index.	required

Returns:

Type	Description
tuple	Multiple single-index tensor expressions.

Examples:

>>> i, j = indices(2); i

\[i\]

>>> i, j, k = indices('i, j, k'); k

\[k\]

>>> I = indices(9); I[0]

\[\#_0\]

Source code in funfact/lang/_tsrex.py

def indices(spec):
    '''Create multiple index varaibles at once.

    Args:
        spec (int or str):

            - If `int`, indicate the number of 'anonymous' index variables to
            create. These anonymous variables will be numbered sequentially
            starting from 0, and are guaranteed to be unique within runtime.
            - If `str`, must be a
            comma/space-delimited list of symbols in the format as described in
            [funfact.index][].

    Returns:
        tuple: Multiple single-index tensor expressions.

    Example:

        >>> i, j = indices(2); i

        $$i$$

        >>> i, j, k = indices('i, j, k'); k

        $$k$$

        >>> I = indices(9); I[0]

        $$\\#_0$$
    '''
    if isinstance(spec, int) and spec >= 0:
        return [index() for i in range(spec)]
    elif isinstance(spec, str):
        return [index(s) for s in re.split(r'[,\s]+', spec)]
    else:
        raise RuntimeError(f'Cannot create indices from {spec}.')