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May 20

PARI/GP question

I don't understand PARI/GP and I'm trying to understand and translate some code. I'm stuck on the line

R = concat(R, p^k*select(x->(x%p),invsigma(n\d,d)) );

I don't know what the select function does (I couldn't find it in references) and I don't know what (x->(x%p) does. Can someone help? Bubba73 ^{You talkin' to me?} 01:24, 20 May 2019 (UTC)[reply]

(01:23) gp > ?select
select(f, A, {flag = 0}): selects elements of A according to the selection
function f. If flag is 1, return the indices of those elements (indirect
selection).

If A is a vector or list, then select(f, A) is the vector or list of the elements x in A for which f(x) is non-zero.

x->(x%p) is the function which takes x to x%p, where p is some value. In other words, x->(x%p) is the function f defined by f(x) = x%p, but "x->x%p" doesn't name the function.

select(x->(x%p),invsigma(n\d,d)) is the elements in invsigma(n\d,d) which are not divisible by p. Example:

(01:30) gp > select(x->x%3,[1,2,3,4,5,6,7])
%4 = [1, 2, 4, 5, 7]

PrimeHunter (talk) 23:44, 20 May 2019 (UTC)[reply]

Thanks, I think I see. Bubba73 ^{You talkin' to me?} 00:04, 21 May 2019 (UTC)[reply]

Online street maps with large text ?

I use Google Maps, but can barely read the text after I take a snapshot with my (non-smart) phone. While still on the PC, I try to zoom in using Google Map's own "+" sign, but that doesn't increase the text size. Zooming in on the Chrome window works ("CTRL +"), but reduces the portion of the screen occupied by the map window to a postage stamp on the lower, right corner. So, is there a way to get large text on a full-sized Google Maps, or with Mapquest or any other utility ? SinisterLefty (talk) 23:42, 20 May 2019 (UTC)[reply]

This is a common problem that has been around for years. There is absolutely no way to increase the font size. In the past, you could trick it into using a font that was slightly larger, but that "bug" was fixed. You are stuck with microscopic text and it will not be fixed. The issue is posted regularly to Google's bug tracker and immediately closed as "known - not a problem." If you have a smart phone, you can turn on disability mode which lets you triple-tap the screen to zoom in the display. Then, you can read the name and triple-tap to close the zoom-in mode. On a computer, you can use the snip tool to take a screenshot, open it in something like Paint, and zoom in. I hope that once there are enough developers at Google who are over 40, they will realize that microscopic text is not useful. If they don't want us to read the street names, just don't clutter up the display with them. But, right now, the cool script kiddies think that a 6-point font is cool. Anyone who doesn't agree is lame. 97.82.165.112 (talk) 01:10, 21 May 2019 (UTC)[reply]

Thanks. And yes, I've used Paint to magnify the map. But even at only 2X it then fills over 4 screens, requiring multiple screen shots on my non-smart phone. I want the text bigger, but not the roads. (This could cause overlapping text, but I'd be willing to risk it.)

Another option is to upload the PC image to my phone, so I can zoom in there without it resizing the text back down or becoming blurry. Lots of extra steps there, though, and lots of zooming and panning on the phone to get text to a readable size. Not the type of thing I'd like to do while stopped at a traffic light. Still, this is the best option I've found so far. SinisterLefty (talk) 06:28, 21 May 2019 (UTC)[reply]

I don't want to answer a question you didn't ask, but in case you're unaware, pretty much any smart phone on the market can run a GPS program (Google Maps or Apple Maps) which will read the street names and directions out loud to you, reducing your need to peer at the screen while driving (a finable offense in some jurisdictions). Matt Deres (talk) 13:23, 23 May 2019 (UTC)[reply]

The problem is not just while driving. It is that Google Maps are practically useless when you are old enough that you can longer read anything smaller than a 12 point font. Google Maps uses a 9 point font for labels, 8 for major roads, 7 for minor roads, and 6 for exit numbers. So, just trying to figure out the name of a store marked on the map is difficult. If you zoom in, it doesn't help. The font size doesn't change. You have to screenshot the map, open it in a different program, zoom in, read the label, realize it isn't what you want, go back to the map, and start over again. This is not a new problem. This has existed since Google Maps began. The children who created it assume that nobody over 40 will ever use Google Maps, so there is no point in making the service accessible. When I personally posed the accessibility issue, I was told by a Google developer (who didn't work on Maps - he worked on their AR game) that you can use Google Maps with a screen reader. So, instead of reading the map, you can have it read out loud. It is an x-y problem. Problem "I can't make the font large enough to read." Solution "Install a screen reader and figure out how to use it." 12.207.168.3 (talk) 13:39, 23 May 2019 (UTC)[reply]

For the phone you can get OsmAnd, it's open source, crap-free and you can separately change the size of text and even of map detail (like showing thicker roads). On the computer I use openstreetmap.org but it has the same kind of problem (since everything is raster) except CTRL + works ok. It can be very slow and hang sometimes though at least it doesn't freeze my browser like Google Maps. It's also very up to date, road changes get added within days for my country, while Google still has had some major streets wrong for nearly a decade. Sadly Google products seem to be trending towards the lowest common denominator and there's nothing we can do about it except try and find something else. 93.136.33.27 (talk) 23:12, 23 May 2019 (UTC) (not 97.82)[reply]

Thanks. Sounds like OsmAnd requires a smart phone, though. I really hate those, as they seem so needlessly complicated. I prefer a flip phone, where it knows to sleep when I close it, and doesn't have to guess after I haven't hit a button for a while that I am done with it. And I would rather get the map the way I want it on my PC, take a snapshot on my flip-phone, and have it be readable there. Looks like that simple process won't work, though. I went ahead and ordered a smart phone (ZTE Z558). Will try that. SinisterLefty (talk) 20:25, 25 May 2019 (UTC)[reply]

I just tried openstreetmap.org. It doesn't look as good as Google Maps, and had a street name wrong that Google Maps has right. It also lacks some of the features Google Maps has, like ability find a given address and get driving directions. But, there is less crap cluttering up the screen as a result, and this is a plus. SinisterLefty (talk) 20:47, 25 May 2019 (UTC)[reply]