Calculate investment's interest rate to break-even insurance cost
60% Downpayment on house?
What does $dx$ mean? $dx$ appears in differential equations, such us derivatives and integrals.  For example, a function $f(x)$ its first derivative is $\dfrac{d}{dx}f(x)$ and its integral $\displaystyle\int f(x)dx$. But I don't really understand what $dx$ is. One-sided limits of $f'(x)$ at a point vs. one-sided limits of the difference quotient at that point I know that if a function is piecewise, then when differentiating it one needs to deal separately with the points of intersection of the pieces, because the derivative may not be defined there.  Also, if a one-sided limit of $f'(x)$ at these "crucial points" is infinite or doesn't exist, it doesn't preclude the limit of the difference quotient from existing and being finite. For example, take $f(x)=x^2\sin\frac1x, f(0)=0$: $f'(x)= 2x\sin\frac1x-\sin\frac1x $ has no limit as $x\to0$ but $\lim\limits_{h\to0}\frac{f(h)-f(0)}{h}=0=f'(0)$.  On the contrary, looking at $f(x)=\sin x +\lvert \sin x\rvert $ on $[0,2\pi]$ one has $f'(x)=2\cos x$ on $(0,\pi) $ and $f'(x)=0$ on $(\pi,2\pi)$ so $\lim\limits_{h\to0^+}f'(\pi+h)\ne\lim\limits_{h\to0^-}f'(\pi+h)$, but they are both finite. And in this case it's easy to find that they agree with the one-sided limits of the difference quotient. Why? Does the finiteness of the former imply that they agree with the latter? Is this also true if the one-sided limits of $f'$ at the crucial points agree with each other? why each left ideal of this is minimal? How do threads work in Python, and what are common Python-threading specific pitfalls? I've been trying to wrap my head around how threads work in Python, and it's hard to find good information on how they operate. I may just be missing a link or something, but it seems like the official documentation isn't very thorough on the subject, and I haven't been able to find a good write-up.  From what I can tell, only one thread can be running at once, and the active thread switches every 10 instructions or so?  Where is there a good explanation, or can you provide one? It would also be very nice to be aware of common problems that you run into while using threads with Python. How to Preload Tabs/Set Multiple Websites as Default in Firefox, IE, etc Any website can set as the homepage of Firefox which loads spontaneously. Is this for multiple tabs? Then BBC Health, CNN, Yahoo Health, msn.com would all extemporarily materialise (in four separate tabs); I then wouldn't have to open each website manually. Wasted screen space due to multiple horizontal bars at the top when an application is open in GNOME desktop Just moved from Unity to GNOME with the update to Ubuntu 17.10. There is a HUGE amount of wasted space at the top of the screen, when an application is open.  Evolution and Firefox both have four "bars" with 90% of each empty. Unity, to its credit was able to blend / mix these horizontal bars so there was only one / two.      Four is way too much. If this is GNOME I may carry on with Unity for the next six months.  Can anybody suggest a tweak/change/fix for this? Using proof by contradiction vs proof of the contrapositive Installing Wi-Fi driver for Realtek Semiconductor RTL8723DE Device [10ec:d723] why can't I edit /proc/sys/kernel/perf_event_max_sample_rate with vi I'm root, running Centos8 on bare mental and permissions on /proc/sys/kernel/perf_event_max_sample_rate are as follows  -rw-r--r--. 1 root root 0 Oct  3 14:00 perf_event_max_sample_rate   I want to change the sample rate by opening this file with vi, making the change and then writing it with either w or w!. When I do so it comes back with  perf_event_max_sample_rate" E667: Fsync failed  When I try to quit, it tells me  E37: No write since last change (add ! to override)   So I can't change the value with vi.  However I can change the value with   echo 4000 &gt; /proc/sys/kernel/perf_event_max_sample_rate   Is this simply because /proc is not a real file system and that all changes to things in /proc would have to be made using echo with a redirect, or maybe sed?  Is this behavior documented somewhere? I read with interest about Einstein's Theory of Relativity and his proposition about the speed of light being the universal speed limit.    So, if I were to travel in a spacecraft at (practically) the speed of light, would I freeze and stop moving?  Would the universe around me freeze and stop moving?  Who would the time stop for? Automatically prefer Ethernet over WLAN Programmatically, how does "rooting" a device enable access? Does Windows 7 allow auto-login with a stored password, like TweakUI did? How can I simplify the use of flags with Views Bulk Operations? I have an administrative display (made with views) that lists content that is pending approval.  In the case of my site, approval means flagging with the approval_for_pub flag (which triggers a custom rule).   allows nodes to be flagged/unflagged all at once by clicking a handy button:    However, upon clicking this button, by default it shows all possible flags and the flag/unflag option:    This is a problem on my site because some of the people responsible for approval get confused by the names of the flags and select the wrong option.  So, what I would like to do is create a VBO option that, when the button is pressed, automatically flags all applicable content with the approval_for_pub flag.  How can I approach this?  It seems like a small detail, but this step happens several times a day, so the chance of making a mistake is quite high. Mars needs water and women I read this book in high school too many years ago for me to think about. Martian colonist are raiding earth's oceans for water and because of the conditions on Mars where only male children are conceived, they are also on the look out for young women as potential mates. Our main character while on a raid, bags not only a young woman but her brother as well. Returning to Mars they find that Earth has attacked Mars can't remember much more. I try to find a good proof for invertibility of strictly diagonally dominant matrices (defined by $|m_{ii}|&gt;\sum_{j\ne i}|m_{ij}|$).  There is a proof of this in  but I'm wondering whether there are are better proof such as using determinant, etc to show that the matrix is non singular. A typical $L^p$ function does not have a well-defined trace on the boundary Count the items from a IEnumerable without iterating? private IEnumerable&lt;string&gt; Tables {     get     {         yield return "Foo";         yield return "Bar";     } }   Let's say I want iterate on those and write something like processing #n of #m.   Is there a way I can find out the value of m without iterating before my main iteration?  I hope I made myself clear. Markov's paper on insolubility of the homeorphy problem I am looking for an English translation of Markov's 1958 paper, On insolubility of the homeorphy problem, which I remember coming across on a website for a computational topology course (taught by Afra Zomorodian). Can you be refused a visitor visa to US if you have bad Credit there? I did my 3 years of College in the US, 2010-2013 due to finance issues I was unable to pay my credit card bill of a certain bank, which still lie unpaid.  However I plan on visiting the US later this year; could I be denied visa for having an unpaid bill ?