MATLAB: How to get the value of exponential power

exponential

Assume that after some computation, matlab give me an output:
a(1)=3.712e-12
a(2)=9.123e-13
How can i got the value of 12 and 13? Assume that a(1) and a(2) is in array a=[a(1) a(2)].
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Edit: to avoid confussion, let me rearrange my question: "Can I get the 'index' (how many zeros in the right of the dot) of the first significant digit from data?". Is this is the only way?
n=1
a(1)=3.712e-12
while 1e1^-n>a(1)
    n=n+1;
end

Best Answer

Just use log10:
>> floor(log10(a))
ans =
  -12  -13
The correct answer is [-12,-13], not [12,13] (because these are the powers of ten), but of course you can lose information if you want with abs.
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