Question

When the numbers are really small, Matlab automatically shows them formatted in Scientific Notation.

Example:

A = rand(3) / 10000000000000000;

A =

  1.0e-016 *

    0.6340    0.1077    0.6477
    0.3012    0.7984    0.0551
    0.5830    0.8751    0.9386

Is there some in-built function which returns the exponent? Something like: getExponent(A) = -16?

I know this is sort of a stupid question, but I need to check hundreds of matrices and I can’t seem to figure it out.

Thank you for your help.

Answer 1

Basic math can tell you that:

floor(log10(N))

The log base 10 of a number tells you approximately how many digits before the decimal are in that number.

For instance, 99987123459823754 is 9.998E+016

log10(99987123459823754) is 16.9999441, the floor of which is 16 – which can basically tell you “the exponent in scientific notation is 16, very close to being 17”.

Floor always rounds down, so you don’t need to worry about small exponents:

0.000000000003754 = 3.754E-012
log10(0.000000000003754) = -11.425
floor(log10(0.000000000003754)) = -12