how can i calculate subset aic using matlab

i have 5 variables in regression model and i want to use aic criterion to choose the correct model i have 2^p (2^5=32 combination) denote variables with x's so the combinations are x1, x2...x5, x1x2, x1x3,...x4x5, x1x2x3.....x3x4x5then 4 variables x1x2x3x4...x2x3x4x5and the last two models are x1x2x3x4x5 and 0 variables are in the model HOW CAN i create simulation to apply aic to the subset models??