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trig |
Function (ROM Call 0x28B) |
Generic subroutine for calculating trigonometric functions.
trig is a TIOS subroutine which is used internally for calculating
trigonometric functions, i.e. in TIOS functions
sin, cos, sincos and
tan. It calculates simultaneously the sine, the cosine and
the tangent of the floating point value pointed to by xptr, and stores the results in
floating point destinations pointed to by sine, cosine and
tangent. The argument pointed to by xptr is assumed to be specified in radians
if deg_flag is 0, or in degrees if deg_flag is 1 (it seems that
these two values are only legal values for deg_flag). Parameter option
is not very clear to me: TIOS uses option = 1 in
sin and sincos, option = 2
in cos, and option = 4 in
tan. I don't know what is the difference between
option = 1 and option = 2, because both the
sine and the cosine are calculated regardless of the value of option.
I only noticed that the tangent will not be calculated if option is not
equal to 4.
Note: I included the description of this routine here only due to completeness: it
is more preferable to call particular trigonometric function instead.
Uses: is_transfinite, _bcd_math
Used by: cos, sin, sincos, tan, handleVarLinkKey, push_trig, ROM Call 0x446