Hi, Found a minor (but annoying to track down!) bug in include/gnuradio/blocks/control_loop.h.
If the input is NaN, then neither of the if statements evaluates to true, and the program segfaults. My company policy requires jumping through some hoops to make a direct github contribution. I suggest a patch: instead of 'int index', make it 'uint8_t index' and that will solve the segfault. static inline float tanhf_lut(float x) { if (x > 2) return 1; else if (x <= -2) return -1; else { int index = 128 + 64 * x; return tanh_lut_table[index]; } } Eugene.