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itrig |
Function (ROM Call 0x28A) |
Generic subroutine for calculating inverse trigonometric functions.
itrig is a TIOS subroutine which is used internally for calculating
inverse trigonometric functions, i.e. in TIOS functions
asin, acos and
atan. It calculates the arc sine, the arc cosine or
the arc tangent of the floating point value pointed to by xptr, and stores the result in
the floating point destination pointed to by result.
The result will be 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 determines which inverse
trigonometric function will be calculated: the arc sine if option = 1,
the arc cosine if option = 2 and the arc tangent if
option = 4. I don't know whether these values are the
only legal values for option, but I believe so.
Note: The parameter xptr is not a pointer to const
value. This means that the value pointed to by it may be changed. In normal
cases this would not appear, but this need not to be true if the structure pointed
to by xptr contains wrong values (for example, arguments out of the function
domain, unnormalized values, etc.).
Uses: is_inf, is_nan, is_sinf, is_transfinite, is_uinf_or_nan, sqrt, _bcd_math
Used by: acos, asin, atan, push_to_sphere