I need the Solution of this equation

If

E=1:0.5:10;
A=2.5;
B=3.18; 
C=4.25;
D=0.15;

then

S = A + B*(lnE/E)+ C*(lnE/E)^2 + D*(E/lnE)

[Matt J]

Everything on the right hand side is known. What's to solve?

[Azzi Abdelmalek]

What is lnE ?

[dashty]

ln E is log(E)

Answer 1

[Azzi Abdelmalek]

syms A B C D E lnE
s=solve(A + B*(lnE/E)+ C*(lnE/E)^2 + D*(E/lnE),lnE)
E=1:0.5:10;
A=2.5;
B=3.18; 
C=4.25;
D=0.15;
out=subs(s)

Answer 2

[Youssef Khmou]

hi,

 A=2.5;
B=3.18;
C=4.25;
D=0.15;
f=@(E) A + B.*(log(E)./E)+ C.*(log(E)./E).^2 + D*(E./log(E))
E=1:0.5:10;
figure, fplot(f,E)
fsolve(f,0)

Answer 3

[Matt J]

I need to fill in a few blanks for myself. If I assume that E is the unknown to solve for (your post seems to say it is a vector of data) and S is supposed to be zero (your post doesn't specify), then there are no real solutions. Your equation is quadratic in lnE/E with roots

>> r=roots([C,B-D,A])

r =

    -0.3565 + 0.6791i
    -0.3565 - 0.6791i

Answer 4

[dashty]

sorry but no one answered correctly

[Azzi Abdelmalek]

Everyone is trying to guess what is your unknown variable, can you provides a clear information about your question?

[dashty]

Dear Azzi thank you for your interest my equation is

S = A + B*(lnE/E)+ C*(lnE/E)^2 + D*(E/lnE)

if A ,B,C,D is constants as the following

A=2.5;

B=3.18;

C=4.25;

D=0.15;

so we want do determine the value of S for all E

and E = (1,2,3,4,5,6,7,8,9,10)

[Jan]

@dashty: "no answer is correctly" is not helpful. 1. It is not clear which answer are concerned by this question, because some answers could be posted afterwards. Of course I can compare the date and time of the answers manually, but this wastes the time of all who want to help you. 2. Instead of mentioning, that they are not correct, a detailed description between the results and your expectations would help to improve the answers. Currently the quality of the answers exceed the information density of the question. Please do not let us guess, what you want.

Answer 5

[Matt J]

    f=@(E) A + B.*(log(E)./E)+ C.*(log(E)./E).^2 + D*(E./log(E))

    S=f(1:10);

Answer 6

[Azzi Abdelmalek]

This is not an equation:

A=2.5;
B=3.18;
C=4.25;
D=0.15;
E=1:10
S=A + B*(log(E)./E)+ C*(log(E)./E).^2 + D*(E./log(E))