[R] Skip jumps in curve

[Duncan Murdoch]

It should be pretty easy to generalize my version of the `plot.gamma()` 
function to a version of `curve()` with an extra `discontinuities` argument.

Duncan Murdoch

On 13/02/2024 1:44 p.m., Leo Mada wrote:
> Dear Duncan,
> 
> Thank you very much for the response. I suspected that such an option 
> has not been implemented yet.
> 
> The plot was very cluttered due to those vertical lines. Fortunately, 
> the gamma function is easy to handle. But the feature remains on my 
> wishlist as useful more in general.
> 
> Sincerely,
> 
> Leonard
> 
> ------------------------------------------------------------------------
> *From:* Duncan Murdoch <murdoch.duncan using gmail.com>
> *Sent:* Tuesday, February 13, 2024 6:05 PM
> *To:* Leo Mada <leo.mada using syonic.eu>; r-help using r-project.org 
> <r-help using r-project.org>
> *Subject:* Re: [R] Skip jumps in curve
> On 13/02/2024 10:29 a.m., Leo Mada via R-help wrote:
>> Dear R-Users,
>> 
>> Is there a way to skip over without plotting the jumps/discontinuities in curve()?
>> 
>> I have not seen such an option, but maybe I am missing something.
>> 
>> plot.gamma = function(xlim = c(-6, -1), ylim = c(-1,3), hline = NULL, n = 1000) {
>>     curve(gamma(x), from = xlim[1], to = xlim[2], ylim=ylim, n=n);
>>     if( ! is.null(hline)) abline(h = hline, col = "green");
>> }
>> 
>> Euler = 0.57721566490153286060651209008240243079;
>> plot.gamma(hline = Euler)
>> 
>> Adding an option to the function curve may be useful:
>> options = c("warn", "silent", "unconnected")
>> 
>> This is part of some experiments in math; but that's another topic. For latest version:
>> https://github.com/discoleo/R/blob/master/Math/Integrals.Gamma.Inv.R 
> <https://github.com/discoleo/R/blob/master/Math/Integrals.Gamma.Inv.R>
> 
> If you know where the discontinuities are, plot multiple times with the
> discontinuities as endpoints:
> 
> plot.gamma = function(xlim = c(-6, -1), ylim = c(-1,3), hline = NULL, n
> = 1000) {
>     start <- floor(xlim[1]):floor(xlim[2])
>     end <- start + 1
> 
>     start[1] <- xlim[1]
>     end[length(end)] <- xlim[2]
> 
>     n <- round(n/length(start))
> 
>     curve(gamma(x), from = start[1], to = end[1], ylim=ylim, n=n, xlim =
> xlim)
>     for (i in seq_along(start)[-1])
>       curve(gamma(x), from = start[i], to = end[i], add = TRUE, n)
>     if( ! is.null(hline)) abline(h = hline, col = "green");
> }
> 
> Euler = 0.57721566490153286060651209008240243079;
> plot.gamma(hline = Euler)
> 
> If you don't know where the discontinuities are, it would be much
> harder, because discontinuities can be hard to detect unless the jumps
> are really big.
> 
> Duncan Murdoch
> 
>