The calculation is A * (1–X) + B*X, where A and B are the colors, and X is the Mix color.
The controls on this rollout let you assign a shader to one of the basic parameters of the Math Color Mix shader. This is comparable to using a map as a component of a standard material; by adding shaders, you can create a shader tree that generates complex effects.
Click the button for a component to display the Material/Map Browser and assign the map or shader. Use the toggle at the left to turn the effect of the map off or on.
The button to the right of each main shader button, for shaders that return multiple parameters, is inactive.