Matrix-variate growth-decay models
  Input-output, growth-decay, production-consumption type situations abound in many practical problems. When the input and output variables are independently gamma distributed, various aspects of the residual effect are already tackled by the author. Matrix-variate analogues, their connections to quadratic and bilinear forms, matrix-variate Whittaker functions, and many properties of such matrix-variate functions, in the real as well as complex case, are discussed here. 
Arak Mathai Mathai