Ptolemy usually makes conversions between these types automatically. The float to complex conversion does the obvious thing, putting the float value into the real part of the complex number and setting the imaginary part to zero. The complex to float conversion computes the magnitude of the complex number.

The Xscope star, and some other stars that generate output, accept "anytype" of input. If the input is complex, the magnitude will be plotted, because it will be cast to a float internally. If you want to plot both the real and imaginary parts you should use the ComplexReal conversion star first.

For technical reasons too involved to explain here, automatic type conversions cannot always be made. In particular, Ptolemy can only do one type conversion for any given output of a star. So if a single output is connected to multiple inputs of different types, Ptolemy may complain. For example, suppose you connect a "float" output to both a "complex" input and a "float" input. Ptolemy will complain. A simple solution is to insert an explicit type conversion. The type conversion stars can be found in the "conversion" palette of the appropriate domain. It will be explained below how to find this. Note that the matrix particle types do not support automatic type conversion at all. Conversion stars need to be explicitly inserted between two stars that work on different Matrix types.

Ptolemy's automatic type conversions have one potentially serious pitfall. Suppose you connect a "float" output to a "complex" and "anytype" input, as shown in figure 2-6