How can I properly format small numbers using num2str?

I was assigned to work on the aesthetics of a table that shows collected data as string.

I want to show the numbers with 4 digits percision, but whenever the number is bigger the 10e-5, the output will include all the zeros, and only the four digits, e.g:

x=0.000123456;
y=0.0000123456;
solx=num2str(x,'%.4G');
soly=num2str(y,'%.4G');
solx

solx = '0.0001235'

soly

soly = '1.235E-05'

Is there any way that I can get solx to be formatted like soly?

Answer 1

[David Hill]

soly=num2str(y,'%.3E')
solx=num2str(x,'%.3E')

[Noam Ouzana]

thanks! but I want the scientific formatting to show only when needed, i.e only when the number has more than four figures, since it's won't always be the case.

I assume that the reason it won't work for the given x value is because the formatting won't really reduce the amount of characters, but I'd still prefer it that way.

[Simon Chan]

Write a function which can change the display format based on the magnitude of the data.

[Walter Roberson]

Simon is correct.

The only conditional formatting that MATLAB supplies in any released version, is what is done automatically by "format short" or "format long", or done by a %g format for sprintf() or fprintf() or compose() -- none of which permit tuning the boundaries of when values are to be shown in which varient.