Save double in txt with specific scientific notation format using writecell

I have a matrix with values in this format:

-4.33826930446975

-4.50867616174965

and I need them written in a *.txt file with this specific notation:

1.305911E-0002

1.101303E-0002

[Jan]

Are you sure, that you want to write the value -4.33826930446975 as "1.305911E-0002"? This is very strange.

Matlab does not offer a way to use 4 digits for the exponent. You have to write this by your own.

[Marcelo Filipchuk]

Not with the exact same value, but with that format. Sorry I wasn't specific with that.

[Jan]

The exact format is: Sign, one digit before the point, 6 digits afterwards, 'E', sign of exponent (even the +?), 4 digits for the exponent?

[Marcelo Filipchuk]

Exactly

[Jan]

What is the wanted output for Inf and NaN?

[Marcelo Filipchuk]

In that case I need the output to be zero.

[Jan]

What have you tried so far and which problems occur? You can use sprintf('%E') and check, if the exponent have 2 or 3 digits. Then replace 'E+' by 'E+0' or 'E+00' (or with '-') accordingly. Alternatively determine the exponent manually using log(abs(x)) and print it and the mantissa using sprintf.

Answer 1

[Walter Roberson]

You probably should be more specific about the rounding or truncation you want to have done for additional digits after the 6th decimal point, paying attention to negatives and to which way '5' should go.

format long g
A = -4.33826930446975

A = 
         -4.33826930446975

B = 0.013059114373

B = 
            0.013059114373

fmt(A)

ans = '-4.338269E+0000'

fmt(B)

ans = '1.305911E-0002'

fmt(nan)

ans = '0.000000E+0000'

fmt(-inf)

ans = '0.000000E+0000'

function output = fmt(X)

    if X == 0 || ~isfinite(X)
       output = '0.000000E+0000';
       return
    end
    D = floor(log10(abs(X)));
    S = X./10.^D;
    output = sprintf('%.6fE%+05d', S, D);
end