sin v/s sinf function in C

Question

I am trying to use the sinf function in my C Program but it gives me an undefined reference error under MSVC 6.0, however sin works fine.

This make me curious to find the difference between sin and sinf.

What is the logical difference between sin and sinf ?

How can I implement my own sinf functionality?

Using a float function to compute the sine is a sinf. – Hans Passant May 15 '10 at 21:07 — Hans Passant, May 15 '10 at 21:07

Paul R · Accepted Answer · 2010-05-15T20:34:31.990

9

sin takes a double and returns a double - sinf takes a float and returns a float.

In other words sin is double precision and sinf is single precision.

If you're using an old compiler that doesn't have sinf you can implement it as:

#define sinf(x) (float)sin((double)(x))

edited May 15 '10 at 20:34

answered May 15 '10 at 20:29

Paul R

score 3 · Answer 2 · answered May 15 '10 at 20:30

3

sin takes a double and returns a double and is defined by ANSI C. sinf isn't.

answered May 15 '10 at 20:30

Apprentice Queue

5

`sinf()` is not standard in C89. It _is_ standard in C99. – James McNellis May 15 '10 at 20:32

score 3 · Answer 3 · answered May 15 '10 at 20:31

3

sinf() was added to C in C99, which Microsoft Visual C++ does not fully support (even so, Visual C++ 6 was released before C99 was standardized).

You can use the sin() function, which takes a double (sinf() takes a float).

answered May 15 '10 at 20:31

James McNellis

3 Answers3