calc: Inverse and Hyperbolic
7.3 Inverse and Hyperbolic Flags
================================
There is no single-key equivalent to the ‘calc-arcsin’ function.
Instead, you must first press ‘I’ (‘calc-inverse’) to set the “Inverse
Flag”, then press ‘S’ (‘calc-sin’). The ‘I’ key actually toggles the
Inverse Flag. When this flag is set, the word ‘Inv’ appears in the mode
line.
Likewise, the ‘H’ key (‘calc-hyperbolic’) sets or clears the
Hyperbolic Flag, which transforms ‘calc-sin’ into ‘calc-sinh’. If both
of these flags are set at once, the effect will be ‘calc-arcsinh’. (The
Hyperbolic flag is also used by some non-trigonometric commands; for
example ‘H L’ computes a base-10, instead of base-e, logarithm.)
Command names like ‘calc-arcsin’ are provided for completeness, and
may be executed with ‘x’ or ‘M-x’. Their effect is simply to toggle the
Inverse and/or Hyperbolic flags and then execute the corresponding base
command (‘calc-sin’ in this case).
The ‘O’ key (‘calc-option’) sets another flag, the “Option Flag”,
which also can alter the subsequent Calc command in various ways.
The Inverse, Hyperbolic and Option flags apply only to the next
Calculator command, after which they are automatically cleared. (They
are also cleared if the next keystroke is not a Calc command.) Digits
you type after ‘I’, ‘H’ or ‘O’ (or ‘K’) are treated as prefix arguments
for the next command, not as numeric entries. The same is true of
‘C-u’, but not of the minus sign (‘K -’ means to subtract and keep
arguments).
Another Calc prefix flag, ‘K’ (keep-arguments), is discussed
elsewhere. 
Keep Arguments.
Info Catalog
calc: Precision
calc: Mode Settings
calc: Calculation Modes