## a journal of the plague year [lost September reviews]

Posted in Books, Kids, Mountains, pictures, Travel with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on December 12, 2020 by xi'an

Read a (red) book I bought in Chamonix last January (sounds like last century, at the very least!) at the Éditions Guérin bookshop, The Bond, by Simon McCartney, translated in French as The Ghosts from Denali. It starts more or less like a traditional mountain climbing story, with a pair of cocky young climbers attacking a new and difficult route and managing the opening despite severe adverse circumstances, which is what Simon McCartney and Jack Roberts did for the north face of Mount Huntington in Alaska, having run out of food and facing the constant threat of collapsing seracs. It however turns into a inner introspection as McCartney gets stranded on the mythical Eiger Nordwand (just like many before him!) after his large group keeps breaking their Charlet Moser icepicks due to the cold (!) and end up being airlifted. He later manages a Winter climb of the Eiger and reunites with Roberts to attempt the south face of Denali, never climbed before. This is when the book takes off, from the sheer difficulty of the route to the amazing unpreparation of the climbers, to Simon’s cerebral embolism building up and bringing him a hair away from death, to the altruism of several other climbers on the mountain to bring him down from the death zone, especially Bo Kandiko, and to a trauma-induced complete break from climbing when McCartney got out of Anchorage hospital. This is gripping and moving and unbelievable. The book received a Banff Mountain Festival award and no wonder. The story told by McCartney is actually seamlessly completed by diary excerpts by Roberts and Kandiko, where they question their own involvement against the very real danger of dying from staying with McCartney, much more than giving up their own attempt against the deadly mountain. A terrific mountaineering book, truly. As a sad coda, Roberts died ice-climbing Bridal Veil Falls a few days before McCartney’s attempt to reunite with him.

Spent several evenings baking fig jam when returning from the Alps as the fig tree was full! And ended up with a total of 35 jars. Resulting into a full “marmalade closet”, as in the past weeks my mom home-made the same amount of peach jelly and my wife’s mom even more rhubarb marmalade jars. Enough to stand a whole year of lockdown, jam-wise. And ate some of the few but tasty peppers that grew in our garden, for the very first time, despite the welcomed tomato and squash invasion! Also ate a terribly greasy risotto in a supposedly highly noted restaurant…

Started watching Dark on Netflix, a German dark time-travel fiction. But while I enjoyed the complex story, the play of the young actors, and the appeal of watching a show (and a Greek play within the show, with Ariádnê and Thêseús of course!) in German, the endless paradoxes of time-travel and the duration of the series made me stop after a few episodes, the town of Winden keeping most of its mystery for me.

## (x=scan())%in%(2*4^(n=0:x)-2^n-1)

Posted in Books, Kids, R with tags , , , , , , , , , on March 28, 2019 by xi'an

One challenge on code golf is to find the shortest possible code to identify whether or not an integer belongs to the binary cyclops numbers which binary expansion is 0, 101, 11011, 1110111, 111101111, &tc. The n-th such number being

$a(n) = 2^{2n + 1} - 2^n - 1 = 2\,4^n - 2^n - 1 = (2^n - 1)(2\,2^n + 1)$

this leads to the above solution in R (26 bits). The same length as the C solution [which I do not get]

f(n){n=~n==(n^=-~n)*~n/2;}

And with shorter versions in many esoteric languages I had never heard of, like the 8 bits Brachylog code

ḃD↔Dḍ×ᵐ≠

or the 7 bits Jelly

B¬ŒḂ⁼SƊ

As a side remark, since this was not the purpose of the game, the R code is most inefficient in creating a set of size (x+1), with most terms being Inf.