how to use the 'solve' function?

hello, im having problem trying to use the solve problem. it's not my first time using it but thata the first time its not working. i have this code line:

tmp = solve('x/L = (1-(h+eta)/ho) - A*log(((h+eta)/ho - A)/(1-A))','eta');

all the parameters are known except 'eta', still it does not provide a solution.

how can i fix it? any sugestions? thank you

Answer 1

[Carlos]

Using arbitrary values for x, h, h0, A and L

>> syms eta;
  >> x=1;h=1;ho=1;A=0.1;L=1;
  >> f=x/L -(1-(h+eta)/ho) - A*log(((h+eta)/ho - A)/(1-A));
  >> eval(solve(f,eta))

    ans =

      -1.1068 - 0.2302i

[Jaimie Ritchie]

This was incredibly helpful to me in learning to use the solve function. I was able to plug in my equation and get a result. Thank you!

Answer 2

[Carlos]

Doing

>> tmp = solve('x/L = (1-(h+eta)/ho) - A*log(((h+eta)/ho - A)/(1-A))','eta')% no semicolon here

tmp =

A*ho - h + (ho - A*ho)/(exp(wrightOmega(log((ho - A*ho)/(A*ho)) - (x/L + h/ho - (h - A*ho)/ho - 1)/A))*exp((x/L + h/ho - (h - A*ho)/ho - 1)/A))

It does give a solution.

Answer 3

[Dany]

thats what im getting too. but i supose to have a numeric answer. i cant use the 'eval' function because it does not recognize 'wrightOmega'.

thats the problem.

Answer 4

[Dany]

ok, thank you Carlos.

i'll give it a try

[Carlos]

I think it should work, just remember to change the values of x,h... Please comment if something does not work by trying my approach to the problem.

Answer 5

[Dany]

sorry Carlos, it still does not work.

i try it with this values (real ones): h = 1.3721, ho = 500, L = 20000, x = 54.8828, A = -1.6452e-008.

and i still get the 'wrightOmega' and no answer .....

Answer 6

[Dany]

ok it works..... thank you

[Carlos]

You are welcome, please mark my answer so people know the answer is correct and can use my answer for their problems.