D2R
int lssign = sin(D2R(lambda)) < 0 ? -1 : 1;
int lcsign = cos(D2R(lambda)) < 0 ? -1 : 1;
while (((sin(D2R(alpha)) < 0) ? -1 : 1) != lssign
|| ((cos(D2R(alpha)) < 0) ? -1 : 1) != lcsign)
#define SIN(x) (sin(D2R(x)))
#define COS(x) (cos(D2R(x)))
#define TAN(x) (tan(D2R(x)))