CTM_COEFF_SIGN
#define CTM_COEFF_NEGATIVE(coeff) (((coeff) & CTM_COEFF_SIGN) != 0)
#define CTM_COEFF_ABS(coeff) ((coeff) & (CTM_COEFF_SIGN - 1))
result[i] |= user_coeff & CTM_COEFF_SIGN;