Color assignment algorithm

As shown above, we set the color to a scalar, at the time of each calibration, such as 5 0 5, 10 and so on when we know his RGB value, but if I want to know the RGB value of 9.9 when we need the algorithm just know, I'm in paraview CXX source code to find for a long time, I did not find this algorithm, can you tell me where she is