Maxima Function
trigrat (expr)
Gives a canonical simplifyed quasilinear form of a
trigonometrical expression; expr is a rational fraction of several sin,
cos or tan, the arguments of them are linear forms in some variables (or
kernels) and %pi/n (n integer) with integer coefficients. The result is a
simplified fraction with numerator and denominator linear in sin and cos.
Thus trigrat linearize always when it is possible.
The following example is taken from Davenport, Siret, and Tournier, Calcul Formel, Masson (or in English, Addison-Wesley), section 1.5.5, Morley theorem.
(%i1) c: %pi/3 - a - b; %pi (%o1) - b - a + --- 3 (%i2) bc: sin(a)*sin(3*c)/sin(a+b); sin(a) sin(3 b + 3 a) (%o2) --------------------- sin(b + a) (%i3) ba: bc, c=a, a=c$ (%i4) ac2: ba^2 + bc^2 - 2*bc*ba*cos(b); 2 2 sin (a) sin (3 b + 3 a) (%o4) ----------------------- 2 sin (b + a) %pi 2 sin(a) sin(3 a) cos(b) sin(b + a - ---) sin(3 b + 3 a) 3 - -------------------------------------------------------- %pi sin(a - ---) sin(b + a) 3 2 2 %pi sin (3 a) sin (b + a - ---) 3 + --------------------------- 2 %pi sin (a - ---) 3 (%i5) trigrat (ac2); (%o5) - (sqrt(3) sin(4 b + 4 a) - cos(4 b + 4 a) - 2 sqrt(3) sin(4 b + 2 a) + 2 cos(4 b + 2 a) - 2 sqrt(3) sin(2 b + 4 a) + 2 cos(2 b + 4 a) + 4 sqrt(3) sin(2 b + 2 a) - 8 cos(2 b + 2 a) - 4 cos(2 b - 2 a) + sqrt(3) sin(4 b) - cos(4 b) - 2 sqrt(3) sin(2 b) + 10 cos(2 b) + sqrt(3) sin(4 a) - cos(4 a) - 2 sqrt(3) sin(2 a) + 10 cos(2 a) - 9)/4