How do i use fzero to solve the following

My code reads as follows:

 time2 = [0:1:4000];

 y = log10(62) - log10(49) - 0.000084*time2;
 fzero(y,1200)

I need to use fzero to calculate the value of time2 when the above equasion is zero. I don't know why it wont work as above but despite my best efforts nothing will stick.

Cheers

p.s. i need to use fzero so alternative solutions, whilst welcome, won't solve my problem.

Answer 1

[Stephen23]

That is not how to use fzero. As its help clearly states and shows, the first argument must be a function handle, which you have not provided. Try this:

>> fun = @(t) log10(62) - log10(49) - 0.00008*t;
>> fzero(fun,1200)
ans =  1277.4

and reading the MATLAB documentation.

[Torsten]

y = 0.5;
fun = @(t) y - (log10(62) - log10(49) - 0.000084*t);
fzero(fun,1200);

[Stephen23]

@Torsten: I think the y in the question is a red herring.

[Liam Wiltshire]

Stephen you are bang on the money there, i couldn't get your original answer to work and unstead used Torstens reply without the y and came to the answer you now have above.

Thank you both very much for you input.

I had already tried using a function handle yesterday when i became stuck, but didn't put t in brackets after the @, so wrote it off.

All sorted now, thank you