| Routines

3843: THE 'ARCCOS' FUNCTION (offset +23)

The address of this routine is found in the table of addresses. It is called indirectly via fp_calc_2. This subroutine handles the function ACS X and returns a real number from 0 to π inclusive which is equal to the value in radians of the angle whose cosine is X. This subroutine uses the relation ACS X=π/2-ASN X.
acs | 3843 | RST $28 | X
| 3844 | DEFB $22 | asn: ASN X
| 3845 | DEFB $A3 | stk_pi_2: ASN X, π/2
| 3846 | DEFB $03 | subtract: ASN X-π/2
| 3847 | DEFB $1B | negate: π/2-ASN X=ACS X
| 3848 | DEFB $38 | end_calc
| 3849 | RET | Finished: 'last value'=ACS X.