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Comment Re:Kids don't understand sparse arrays (Score 1) 128 128

It all depends on what you want to do with your matrices. Various operations have various costs in different sparse matrix formats. The standard ones are COO or coordinate format: a list of triples (i, j, val); DOK or dictionary of keys format: the hashmap you are thinking of; LIL or list of lists format: a list for each row and a list if pairs (j, val) in each list entry; CSR/CSC or compact sparse row/column: an array of indices where each row starts, an array of column indices and an array of values.

COO and DOK are great for changing sparsity structure; LIL is very useful if you have a lot of row-wise (or column-wise) operations, or need to manipulate rows regularly. CSR is great for matrix operations such as multiplication, addition etc. You use what suits your usecase, or change between formats (relatively cheap) as needed.

Comment Re:Cambridge, England (Score 1, Interesting) 266 266

Wish I had mod points.

I would point out though that Apple were one of the original investors in ARM. They even helped with the early (though not the initial) silicon design.

The article is also wrong on other points. I've had two companies in the UK, the first failed (and I didn't really feel any "stigma". It just didn't work out); the second (which contained mainly the same people as the first) was bought up, which is why I'm over in Sunny CA now rather than back in London...

The social net is actually a lot stronger in the UK I feel (as someone who's lived in the US for the last decade), so having a company fail on you isn't the enormous burden that it is in the USA. There's a lot of ways/government help to get back on your feet in the UK that still don't really exist in the USA; and, of course, there's things like government-sponsored healthcare so you don't *need* to be employed just to cover your arse on essential things like that.

Just my $0.02/£0.01 (rounding up)

Simon.

Comment Re:a low-IQ child's IQ can be raised in some cases (Score 2) 185 185

I've had sat psychologist administered IQ tests a year apart and had my score differ by 10 points. I've been told that, in fact, this is perfectly normal and well within the accuracy expected of IQ tests by psychologists who take them seriously. I wouldn't worry about IQ scores changing (they may well do that, but it is equally likely measurement error). IQ is a very imperfect measure to begin with. Our ability to measure it, even under the best of conditions, is extremely poor. Take most IQ studies with a grain of salt.

Comment Re:The Road Warrior (Score 1) 776 776

...not a sequel, but a cash-in remake.
It's not a Mad Max movie. The main character isn't Max, the atmosphere isn't Mad Max's, it just happened to have spiked cars chasing plated cars in the wastland.

Indeed. What they should have done was get the writer/director of the original film, who I gather had been trying to get a sequel made for over a decade, to come and write and direct the new one. Clearly whoever they got to write this didn't really understand Max's character at all.</sarcasm>

Comment Re:what will be more interesting (Score 1) 662 662

Fortunately the comment history is preserved. Not 5 posts up you state, and I quote:

"Most Americans don't understand just how restricted speech is in the UK by comparison to the US"

Restriction of free speech pertains to government restriction. We don't care what companies / institutions do. The BBC isn't the government.

So, I guess the gp was correct.

Comment Re:Check their work or check the summary? (Score 2) 486 486

And this is why we should not teach CS101 in Java or Python. If they'd been forced to use C this whole experiment would have turned out differently.

Not at all. If you wrote your C in memory string handling as stupidly as they wrote the Python and Java you will still get worse performance in C (e.g. each iteration malloc a new string and then strcpy and strcat into it, and free the old string; compared to buffered file writes you'll lose). It's about failing to understand how to write efficient code, not about which language you chose.

Comment Re:disclosure (Score 2) 448 448

I'm guessing the reason he doesn't take money from the fossil fuel industry is because he just can't be bothered with such trifling sums. The average salary in the US is more like $350k or $400k, IIRC. 120k is for total losers.

I can only presume your talking about research grants combined with salary, despite saying "The average salary" because otherwise you are simply flat wrong. The average salary for (full) professors in the US is $98,974.

Comment Re:On a related note: (Score 1) 291 291

Should we teach everyone basic first aid and CPR, fundamentals of mechanics, and the basics of how to sew, cook, etc.? Yes, yes we should.

I don't think the "Teach Everyone to Code" movement is about making everyone professional programmers; it's about ensuring that everyone gets exposed the basics of how programming works, just like they get exposed to the basics of a great many other things in their schooling.

Submission + - Mathematicians Study Effects of Gerrymandering on 2012 Election 1 1

HughPickens.com writes: Gerrymandering is the practice of establishing a political advantage for a political party by manipulating district boundaries to concentrate all your opponents votes in a few districts while keeping your party's supporters as a majority in the remaining districts. For example, in North Carolina in 2012 Republicans ended up winning nine out of 13 congressional seats even though more North Carolinians voted for Democrats than Republicans statewide. Now Jessica Jones reports that researchers at Duke are studying the mathematical explanation for the discrepancy. Mathematicians Jonathan Mattingly and Christy Vaughn created a series of district maps using the same vote totals from 2012, but with different borders. Their work was governed by two principles of redistricting: a federal rule requires each district have roughly the same population and a state rule requires congressional districts to be compact. Using those principles as a guide, they created a mathematical algorithm to randomly redraw the boundaries of the state’s 13 congressional districts. "We just used the actual vote counts from 2012 and just retabulated them under the different districtings," says Vaughn. "”If someone voted for a particular candidate in the 2012 election and one of our redrawn maps assigned where they live to a new congressional district, we assumed that they would still vote for the same political party."

The results were startling. After re-running the election 100 times with a randomly drawn nonpartisan map each time, the average simulated election result was 7 or 8 U.S. House seats for the Democrats and 5 or 6 for Republicans. The maximum number of Republican seats that emerged from any of the simulations was eight. The actual outcome of the election — four Democratic representatives and nine Republicans – did not occur in any of the simulations. "If we really want our elections to reflect the will of the people, then I think we have to put in safeguards to protect our democracy so redistrictings don't end up so biased that they essentially fix the elections before they get started," says Mattingly. But North Carolina State Senator Bob Rucho is unimpressed. "I'm saying these maps aren't gerrymandered," says Rucho. "It was a matter of what the candidates actually was able to tell the voters and if the voters agreed with them. Why would you call that uncompetitive?"

"What I've done, of course, is total garbage." -- R. Willard, Pure Math 430a

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