EPTThe Big Programming Thread - Page 866
| Forum Index > General Forum |
Thread Rules 1. This is not a "do my homework for me" thread. If you have specific questions, ask, but don't post an assignment or homework problem and expect an exact solution. 2. No recruiting for your cockamamie projects (you won't replace facebook with 3 dudes you found on the internet and $20) 3. If you can't articulate why a language is bad, don't start slinging shit about it. Just remember that nothing is worse than making CSS IE6 compatible. 4. Use [code] tags to format code blocks. | ||
|
Nesserev
Belgium2760 Posts
| ||
WarSame
Canada1950 Posts
| ||
|
Manit0u
Poland17783 Posts
On March 31 2017 09:24 WarSame wrote: Thanks! That's what all the answers are talking about with typedefs, right? The ability to alias a more complicated name for a simpler name? Here's a nice example: http://ee.hawaii.edu/~tep/EE160/Book/chap14/subsection2.1.3.1.html And here's a more convoluted explanation: http://stackoverflow.com/questions/10758811/c-syntax-for-functions-returning-function-pointers | ||
|
Manit0u
Poland17783 Posts
| ||
|
Deleted User 3420
24492 Posts
is the column space of a matrix the same as the basis of a set of vectors that compose that matrix ? | ||
|
Prillan
Sweden350 Posts
On March 31 2017 21:30 travis wrote: linear algebra question is the column space of a matrix the same as the basis of a set of vectors that compose that matrix ? The column space is, by definition, the span of the column vectors. I have no idea what you're trying to say in the second part. | ||
|
Djagulingu
Germany3605 Posts
On March 31 2017 19:09 Manit0u wrote: https://www.youtube.com/watch?v=VgC4b9K-gYU We are rolling this feature out to most users on March 31, and all accounts will have access by April 1. and all accounts will have access by April 1. will have access by April 1. by April 1. April 1. April 1 April 1 April 1 April 1 . . . APRIL FOOLS GUYS :D:D:D | ||
|
Deleted User 3420
24492 Posts
On March 31 2017 23:36 Prillan wrote: The column space is, by definition, the span of the column vectors. I have no idea what you're trying to say in the second part. what I mean is for an nxn matrix, is the basis of it's column space the same as a basis for the matrix itself. like if I have a question that gives me 5 vectors of 5 variables each that comprise a vector space and it asks me to find the basis of the vector space do I just find the pivot columns and then those vectors are the basis? | ||
|
CoughingHydra
177 Posts
And yes, pivot columns (I assume that by this you mean the vectors you get by Gaussian elimination with only column operations) are one of the possible bases for the space the original five column vectors span. | ||
|
emperorchampion
Canada9496 Posts
| ||
|
emperorchampion
Canada9496 Posts
On April 01 2017 01:00 travis wrote: what I mean is for an nxn matrix, is the basis of it's column space the same as a basis for the matrix itself. like if I have a question that gives me 5 vectors of 5 variables each that comprise a vector space and it asks me to find the basis of the vector space do I just find the pivot columns and then those vectors are the basis? To this yes (although I think your wording is wrong) the matrix will contain n out of the infinite possible columns in the column space that is defined by the basis. | ||
|
Acrofales
Spain18356 Posts
"Pivot columns" will not automatically form the basis. If you follow a suitable algorithm then yes, your pivot columns will form the basis, but if you choose the pivots wrong (lets say, picking random elements), then you'll just end up with a mess, rather than linearly independent vectors. | ||
|
emperorchampion
Canada9496 Posts
On April 01 2017 02:31 Acrofales wrote: Wait. Won't it depend on what pivots you choose whether your pivot columns will form a basis for your matrix? "Pivot columns" will not automatically form the basis. If you follow a suitable algorithm then yes, your pivot columns will form the basis, but if you choose the pivots wrong (lets say, picking random elements), then you'll just end up with a mess, rather than linearly independent vectors. This is due to numerical errors in a GE procedure though if I understand correctly | ||
|
CoughingHydra
177 Posts
| ||
|
Hanh
146 Posts
| ||
|
Zess
Adun Toridas!9144 Posts
jQuery("div.watched-badge").parents("ol.item-section").parent("li").remove();I have almost no javascript knowledge, but based on a 20 minute documentation read, it seems that it is very difficult to traverse parent DOM elements while trivial to traverse child elements with querySelector It seems that my best option is to 1) grab all of the "div.watched-badge" elements of the page 2) manually loop over each element's parent until I get to "ol.item-section" and then grab it's parent and remove it The reason why I want to do this without jQuery is that this code cleans up my youtube subscription feed of watched videos (who knows why that doesn't happen by default) and I want to turn it into a bookmark or extension, so I feel that doing it in a way that doesn't require loading jquery into the page is probably the best (right now I'm manually injecting a jquery script in from their cdn and then running that code into the console). | ||
|
Nesserev
Belgium2760 Posts
| ||
|
Deleted User 173346
16169 Posts
| ||
|
Prillan
Sweden350 Posts
On April 01 2017 01:00 travis wrote: like if I have a question that gives me 5 vectors of 5 variables each that comprise a vector space and it asks me to find the basis of the vector space do I just find the pivot columns and then those vectors are the basis? Basically, yes. (As Hanh pointed out) Put your vectors as columns in a matrix and reduce it with Gauss-Jordan elimination. See this for an example: https://en.wikipedia.org/wiki/Row_and_column_spaces#Basis As a former teacher in linear algebra, please take care when using the different terms. They are precisely defined and should be used as such. "5 vectors of 5 variables": vectors don't have variables. Did you mean 5 vectors in R^5? "it asks me to find the basis of the vector space": a basis. There are (usually) infinitely many choices for a basis. "then those vectors are the basis": same here. "for an nxn matrix, is the basis of it's column space the same as a basis for the matrix itself.": I don't know what "a basis for the matrix" means. Is this something your professor has defined? | ||
tofucake
Hyrule19228 Posts
On April 01 2017 17:00 Zess wrote: What's the best way to translate this javascript that relies on jQuery object to be pure javascript? jQuery("div.watched-badge").parents("ol.item-section").parent("li").remove();I have almost no javascript knowledge, but based on a 20 minute documentation read, it seems that it is very difficult to traverse parent DOM elements while trivial to traverse child elements with querySelector It seems that my best option is to 1) grab all of the "div.watched-badge" elements of the page 2) manually loop over each element's parent until I get to "ol.item-section" and then grab it's parent and remove it The reason why I want to do this without jQuery is that this code cleans up my youtube subscription feed of watched videos (who knows why that doesn't happen by default) and I want to turn it into a bookmark or extension, so I feel that doing it in a way that doesn't require loading jquery into the page is probably the best (right now I'm manually injecting a jquery script in from their cdn and then running that code into the console). You'd basically have to go in reverse, start with a document.getElementsByClassName('item-section') and then traverse that and pick out the watched-badge subnodes | ||
| ||
