delaylinebackward

delay_line_backward([rng], [T], dims...;
    weight=0.1, fb_weight=0.1, return_sparse=false,
    delay_kwargs=(), fb_kwargs=())

Create a delay line backward reservoir with the specified by dims and weights. Creates a matrix with backward connections as described in (Rodan and Tino, 2011).

Arguments

• rng: Random number generator. Default is Utils.default_rng() from WeightInitializers.
• T: Type of the elements in the reservoir matrix. Default is Float32.
• dims: Dimensions of the reservoir matrix.

Keyword arguments

• weight: The weight determines the absolute value of forward connections in the reservoir. This can be provided as a single value or an array. In case it is provided as an array please make sure that the lenght of the array matches the lenght of the sub-diagonal you want to populate. Default is 0.1

• fb_weight: Determines the absolute value of backward connections in the reservoir. This can be provided as a single value or an array. In case it is provided as an array please make sure that the lenght of the array matches the lenght of the sub-diagonal you want to populate. Default is 0.1.

• fb_shift: How far the backward connection will be from the diagonal. Default is 2.

• return_sparse: flag for returning a sparse matrix. Default is false.

• delay_kwargs and fb_kwargs: named tuples that control the kwargs for the delay line weight and feedback weights respectively. The kwargs are as follows:

  • sampling_type: Sampling that decides the distribution of weight negative numbers. If set to :no_sample the sign is unchanged. If set to :bernoulli_sample! then each weight can be positive with a probability set by positive_prob. If set to :irrational_sample! the weight is negative if the decimal number of the irrational number chosen is odd. If set to :regular_sample!, each weight will be assigned a negative sign after the chosen strides. strides can be a single number or an array. Default is :no_sample.
  • positive_prob: probability of the weight being positive when sampling_type is set to :bernoulli_sample!. Default is 0.5.
  • irrational: Irrational number whose decimals decide the sign of weight. Default is pi.
  • start: Which place after the decimal point the counting starts for the irrational sign counting. Default is 1.
  • strides: number of strides for assigning negative value to a weight. It can be an integer or an array. Default is 2.

Examples

julia> res_matrix = delay_line_backward(5, 5)
5×5 Matrix{Float32}:
 0.0  0.1  0.0  0.0  0.0
 0.1  0.0  0.1  0.0  0.0
 0.0  0.1  0.0  0.1  0.0
 0.0  0.0  0.1  0.0  0.1
 0.0  0.0  0.0  0.1  0.0

julia> res_matrix = delay_line_backward(Float16, 5, 5)
5×5 Matrix{Float16}:
 0.0  0.1  0.0  0.0  0.0
 0.1  0.0  0.1  0.0  0.0
 0.0  0.1  0.0  0.1  0.0
 0.0  0.0  0.1  0.0  0.1
 0.0  0.0  0.0  0.1  0.0