Computationally efficient method to convolve a vector of observations and a single exponential function with two parameters.
expConv(input, k1, k2)is the so-called input function.
is the scaling parameter in the single exponential function.
is the decay parameters in the single exponential function.
The vector containing the result from the convolution operation.
Assuming the input function has been sampled (or interpolated) to a high temporal resolutions, say one Hertz, a simple for loop is used to perform the convolution.