 What's the function of a function variable's function? - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- Thread: What's the function of a function variable's function? (/thread-2354.html) What's the function of a function variable's function? - DrD - 10-29-2014 12:24 PM Interestingly, I found nothing in the user guide regarding this usage of a function variable: CAS enter: r(t):=[t-sin(t) 1-cos(t)] Produces: r:=(t)->BEGIN [t-sin(t),1-cos(t)]; END; (t)->BEGIN [t-sin(t),1-cos(t)]; END; Example: A revolving cycloid at t=0 (rest), position r(0) => [0,0] rotates to pi radians, r(π) => [π,2], completes a full cycle at r(2*π) => [2*π,0]. Is there any further information on this? -Dale- RE: What's the function of a function variable's function? - Han - 10-29-2014 02:18 PM You can find more info by looking at the documentation for xcas/giac. There isn't anything special about a variable whose content is a function. It's supposed to reflect a mathematical function. So you can create functions by simply using the form: function_name(var_name):= ; This is typical for any CAS. The CAS also knows how to handle functional algebra. So you can define two functions f(x) and g(t) and ask the CAS to compute h:=f+g, and then use compute, say, h(3). RE: What's the function of a function variable's function? - DrD - 10-29-2014 03:22 PM The fact that it created the function in much the same way as 'Define' might, was new to me. The 'BEGIN and END' surround wasn't something I expected, but now that I have learned of that behavior, I imagine it will become quite useful. Thanks for the xcas/giac reference. -Dale-