tan() Mathematics Function (libm) tan() Calculate tangent #include <math.h> double tan(radian) double radian; tan calculates the tangent of its argument radian, which must be in radian measure. ***** Example ***** For an example of this function, see the entry for acos. ***** See Also ***** mathematics library, tanh() ***** Diagnostics ***** tan returns a very large number where it is singular, and sets errno to ERANGE. COHERENT Lexicon Page 1