Solve Logrithm Equation with multiple solutions

I am trying to solve an equation using:

solve('(1.581/1.5)=x*log(58/x)')

ans =

56.936183721096301740573270965739

However, there is another solution 0.183, which matlab does not give me and that happen to be the solution I need. How to solve it? Thanks!

Answer 1

[Matt Fig]

Just use numerical methods:

f = @(x)(1.581/1.5)-x.*log(58./x);
rt = fzero(f,.2)

[Matt Fig]

Carol comments,

"Thanks Matt, so the trick is for discontinuous function, you got to define the range for its solution?"

[Matt Fig]

When using FZERO you have to supply an initial guess or a bracket. See the help for more information.

help fzero