Hello Doug, First I would like to thank you for your reply! Second, I understand that evalf is not a simple "rounding"-tool, but I would like to understand what is happening when I use it. When I enter evalf(sin(Pi/8),2); what exactly is calculated? It's not sin(3.14/8) or sin(0.39)! I would like to reproduce the answer 0.36 on a simple calculator. Greets, Jan

Hello Doug, First I would like to thank you for your reply! Second, I understand that evalf is not a simple "rounding"-tool, but I would like to understand what is happening when I use it. When I enter evalf(sin(Pi/8),2); what exactly is calculated? It's not sin(3.14/8) or sin(0.39)! I would like to reproduce the answer 0.36 on a simple calculator. Greets, Jan