Is there a built-in way to convert/toggle between GNU Emacs Calc's HMS forms and seconds? I'd also like to easily be able to add numbers as seconds and/or minutes to an existing HMS form.
One way of going from an HMS form to the number of seconds is hinted by a line from the HMS forms page:
Dividing two HMS forms produces a real-valued ratio of the two angles.
So if an HMS form is on the stack
5@ 30' 0"
entering one second to the stack
and dividing by it
gives the number of seconds:
Not exactly a convert but it's only three keystrokes.