# How do i use fzero to solve the following

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Liam Wiltshire 2018 年 1 月 9 日
コメント済み: Liam Wiltshire 2018 年 1 月 9 日
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.

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### 採用された回答

Stephen23 2018 年 1 月 9 日

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
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Stephen23 2018 年 1 月 9 日
@Torsten: I think the y in the question is a red herring.
Liam Wiltshire 2018 年 1 月 9 日
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

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