Example 2

The program

  process = ffunction(int fn(int), "<math.h>", "-lm");

compiles to

  ...
  /* link with : "-lm" */
  #include "<math.h>"
  ...
  virtual void compute(int count, FAUSTFLOAT** inputs, FAUSTFLOAT** outputs) {
    FAUSTFLOAT* input0 = inputs[0];
    FAUSTFLOAT* output0 = outputs[0];
    for (int i = 0; (i < count); i = (i + 1)) {
      output0[i] = FAUSTFLOAT(int(fn(int(float(input0[i])))));
    }
  }
  ...

Note the explicit float to int conversions.

A foreign function can have zero or more input arguments, and it must return a single FAUSTFLOAT as output.