This function uses control C [0 to 1.0] to pick a value from the 
The value returned will of the same data type as the samples.

This input (C) controls the linear interpolation for the samples (S),
and is used to pick the interpolated return value.
This value must be a scalar.

These are the input samples (S) to interpolate betweeen.
The samples may be scalars, vectors, or colors.
All samples must be of the same data type.

Returns a value (OUT) based on a linear interpolation of samples (S)
controlled by scalar C. 
The value returned will of the same data type as the input samples.