276 reputation
114
bio website ziga-lausegger.netau.net/…
location Slovenia
age 28
visits member for 2 years, 7 months
seen Nov 26 '13 at 13:11

I love to program and crosscompile baremetal C programs for ARM based microcontrollers, I love physics and i love writing science documents/books in LaTeX. It amazes me how physics is connecting all science and is helping mathematics to evolve. In order for science profession to comunicate on a high level i advise everyone to use Linux, LaTeX and a good vector imaging program like Inkscape.


Aug
12
comment How do we calculate this exponential integral if we change limit from $\infty$ to $x_1$
It doesn't even have a $\sinh$, $\cosh\dots$. It is not programable. Can you recommend any good calculator to calculate integrals?
Aug
12
comment How do we calculate this exponential integral if we change limit from $\infty$ to $x_1$
Well my calculator lacks it :)
Aug
12
comment How do we calculate this exponential integral if we change limit from $\infty$ to $x_1$
Does this mean this can only be solved using numerical methods?
Aug
12
comment Some exponential integrals - I need algebraical solution besides my graphical one
Knowing this rule can save A LOT of integration per partes :)
Aug
12
comment How do we calculate this exponential integral if we change limit from $\infty$ to $x_1$
Thank you. Is the error function really necessary :/ ???
Aug
12
comment Some exponential integrals - I need algebraical solution besides my graphical one
I know that $\int_{-\infty}^0 = - \int_{0}^{-\infty}$ but if i want to know what happens if i insert $-x$ instead of $x$ i have to check what function i have. In my case it is odd so i should get the change in sign also... Does this mean that $\int_{-\infty}^{0}=-\int_{\infty}^{0}$ AND $\int_{0}^{\infty}=-\int_{0}^{-\infty}$ ???
Aug
12
comment How do we calculate this exponential integral if we change limit from $\infty$ to $x_1$
I din't change it. I have to solve the later integral which has $x_1$ for limit. But i found the first integral in the mathematics manual.
Aug
12
comment Some exponential integrals - I need algebraical solution besides my graphical one
So to solve these types of problems we use the known integral (which is not definite): $\int x e^{-ax^2}dx= - \frac{1}{2a}e^{-ax^2}dx$ again and again using the perpartes. If i understood right this is the philosophy behind this case. Does this formula has a derivation? Please point me to it.
Aug
12
comment Some exponential integrals - I need algebraical solution besides my graphical one
But $d/dx\,e^{ax^2}=2ax\,e^{ax^2}$ I don't understand why above isn't true...
Aug
12
comment Some exponential integrals - I need algebraical solution besides my graphical one
One more thing. Isn't it $\int e^{ax^2}dx = \frac{1}{2ax}e^{ax^2}$?
Aug
12
comment Some exponential integrals - I need algebraical solution besides my graphical one
I like hints like this one :)
Aug
12
comment Some exponential integrals - I need algebraical solution besides my graphical one
Your case is for the $x$ what about for the $x^2$?
Aug
12
comment Some exponential integrals - I need algebraical solution besides my graphical one
Oh i forgot to mention that $n,~a \in \mathbb{N}$.
Aug
12
comment Some exponential integrals - I need algebraical solution besides my graphical one
I would like to analytically show, that they equal 0. Check my Edited Question. I was thinking to solve them using the relation described there, but i get spapped limits and a negaitve sign... Long story short, I need to know what are the relations between $$\int\limits_{0}^{\infty} dx \qquad \int\limits_{0}^{-\infty} dx \qquad \int\limits_{\infty}^{0} dx \qquad \int\limits_{-\infty}^{0}$$
Aug
2
comment Trigonometric functions
Yes. I need to know how to get RHS out of LHS. I tried to use the double angle trigonometric identity and it only got more complicated...
Aug
2
comment Short integral question
I think i understand everything now exept this: $\left.-\pi\int\limits_0^\infty(-2r\,dr)e^{-r^2}=-\pi e^{-r^2}\right|_0^\infty$ How do you do this?
Aug
2
comment Short integral question
@DonAntonio but i am using a Google Chrome it is the best :)
Aug
1
comment Short integral question
I upvoted all of you (I hope it helps). This wouldn't be the first time this happened. This page is somehow bugged it seems.
Aug
1
comment Short integral question
Oh i did ... But i didn't know. It happened because this page is jumping up and down while those advertisments are loading. I fixed the downvote.
Aug
1
comment Short integral question
I downvoted noone ...