Hello list, I found out that declaring arrays in this way: float a[], b[]; is buggy, as it seems the type for b[] is not taken as float. Maybe something else happens here (maybe passing by ref), I haven't check thoroughly (don't know if it happens with other types as well). See the following code: // ******************************* // this works: // ******************************* float freq, amp; fun void Do( float freq, float amp) { <<<"do sthg">>>; } Do(freq,amp); // ******************************* // also works: arrays declared in separate lines // ******************************* float freq1[1]; float amp1[1]; fun void Do( float freq[], float amp[]) { <<<"do sthg">>>; } Do(freq1,amp1); // ******************************* // throws error :argument type(s) do not match // arrays declared in the same line // ******************************* float freq2[1], amp2[1]; Do(freq2,amp2);