# Search results

1. ### I Need Aproximate expressions for : ln(x) and 1/ln(x) Thanks

Hi there: I am looking for approximate expressions for the two functions: ln(x) and 1/ln(x) . Any help? Thanks in advance.
2. ### A Linear Systems

In order to find the Impulse response , f(t), you need only the real part , R(ω),of the transfer function F(j ω). According to the mentioned paper: f(t)= (2/π).∫R(ω).cos(tω) dω The limits of integration are from zero to infinity. Best regards
3. ### A Linear Systems

Dear friends: Thanks for your kind comments. In the meantime I could find a direct straightforward answer in the 1959 publication: SIMPLIFED METHOD OF DETERMINING TRANSIENT RESPONSE FROM FREQUENCY RESPONSE OF LINEAR NETWORKS AND SYSTEMS By: Victor S . Levadi Thanks again. Boudy
4. ### A Linear Systems

The transfer function of a linear system is known in the sinusoidal frequency domain. It is given in its final form as a complex function of the angular frequency ω (not jω ). How to obtain the step response? Thanks in advance.
5. ### A Solving two simultaneous integro-differential equations

I thank both friends for their kind help. Fortunately, and after some modifications in the equations, a solution was possible using the numerical solution of two simultaneous differential equations in two variables and one single independent variable. This was done using the NDSolve command...
6. ### What software do you use in your field of study?

1. I am using (Mathematica) since eary 1990's. I went through all its versions from (Mathematica 5. to (Mathematica 11). It helped my alot specially when dealing with calculus and graphic illustrations. 2. I use (Miceosoft Word) and (PowerPoint). 3. My current Browser is (Maxthon...
7. ### A Solving two simultaneous integro-differential equations

I am trying to find a closed-form (analytical) solution for the two following simultaneous integro-differential equations : du[x]/dx= - a v[x] +b ∫〖[1-(y-x)^4 〗].(v[y]-v[x])dy And (dv[x])/dx= - f u[x] -g ∫〖[1-(y-x)^4 〗].u[y]dy With the initial conditions: v[0]=e and u[1]=0 a,b,f,g...