# Recent content by Belgium 12

1. ### A Psi function or digamma function?

Hi everyone, concerning serie representation of psi function. In te solution of bessel function of the second kind we have the following expressions for the psi functions psi(m+1) and psi(n+m+1) then they give the series for the two psi functions ie(or digamma function) sum k from 1 to m of...
2. ### A Question about computing residues after substitution

Hi, thank you very much for the answer Belgium 12
3. ### A Question about computing residues after substitution

Hi members, See attacged PDF file for my question Thank you
4. ### A Residues of gamma functions

Hi members, I have a problem with the computation of residues involve the gamma functions. (see attached Pdf file) Can you show me for the first residue with the arrows, or give a hint or a link. Thank you
5. ### I Series expansions of log()

Hi, see attached PdF file for my question concerning serie expansion of log(z) at infinity. Thank you Belgium 12
6. ### I Differentiation notation

Hi members, see attached PdF file. What's the difference between d/dx and d/d(x^2) I don't understand this notation?? Thank You
7. ### I Laplace transform using differential equations

Hello Mark 44, If I understand it,Y'(0)=infinity.Here infinity can be treated as a constant. Thank you
8. ### I Laplace transform using differential equations

Hi members, Laplace transform using differential equations.(see attached PDF file) My question d/ds(s^2 y- s Y(0)-Y'(0).)....... Y(t)=sin(sqrt(t)) Y(o)=0 Now Y'= cos(sqrt(t)/2sqrt(t) Y'(0)=infinity d/ds (Y'(0)=?? can it be treated as a constant or can we change limit and...
9. ### Integrals log x in terms of dilogarithm

Hi members, see attached PdF file.Have you any idea to prove thes integrals Thank you
10. ### Substitution in integral

Hi members, see attached Pdf file. For a<0,write b=-a and let x=bt.Then My question: how becomes the denominator x+a to 1-t??? I don't see it Thank you
11. ### Gamma function and factorial

Hi members, gamma (n+1)=n! Now I have the following: gamma(2(n+3/2))=gamma(2n+1) What is factorial notation for this?? Thank you
12. ### To pwsnafu integral sinh^2(x/2)

Hi dear members, Sorry for my mistake with coth(x/2). to pwsnafu:I want to integrate integral from -inf to +inf of 1/sinh^2(x/2) Thank you
13. ### Integral of 1/sinh^2(x/2)

Hi dear members, I have a problem with the following integral: Integral 1/sinh^2(x/2) from -inf to +inf =-2 coth(x/2) must I consider it as a principal value integral??? Thank you
14. ### Summation with exponential functions

Dear members, see attached pdf file.Can you help me to prove this formulas. Thank you Belgium 12 This is not homework.I'm 68 and retired.
15. ### Fourier transforms

Hi members, I have a problem with fourier transforms. There are two attached Pdf files. My questions are on the Pdf files.Give me a little help. Thank you Belgium 12