RepeatChannels

An auxiliary graph element that repeats the channels of an input signal, allowing for example for an exhaustive element-wise combination with another signal.

Normally, the way multi-channel expansion works is that when two signals are combined, the output signal has a number of channels that is the ''maximum'' of the individual number of channels, and channels will be automatically wrapped around.

For example, in x * y if x has three and y has five channels, the result expands to

Seq[GE](
 x.out(0) * y.out(0), x.out(1) * y.out(1),
 x.out(2) * y.out(2), x.out(0) * y.out(3),
 x.out(1) * y.out(4)
)

Using this element, we can enforce the appearance of all combinations of channels, resulting in a signal whose number of channels is the ''sum'' of the individual number of channels.

For example, RepeatChannels(x, 5) expands to

Seq[GE](
 x.out(0), x.out(0), x.out(0), x.out(0), x.out(0),
 x.out(1), x.out(1), x.out(1), x.out(1), x.out(1),
 x.out(2), x.out(2), x.out(2), x.out(2), x.out(2)
)

And RepeatChannels(x, 5) * y accordingly expands to the fifteen-channels signal

Seq[GE](
 (x out 0) * (y out 0), (x out 0) * (y out 1), (x out 0) * (y out 2), (x out 0) * (y out 3), (x out 0) * (y out 4),
 (x out 1) * (y out 0), (x out 1) * (y out 1), (x out 1) * (y out 2), (x out 1) * (y out 3), (x out 1) * (y out 4),
 (x out 2) * (y out 0), (x out 2) * (y out 1), (x out 2) * (y out 2), (x out 2) * (y out 3), (x out 2) * (y out 4)
)