Fprintf Numerical Specifiers for fixed number of integers ?

Hi All,

Quick question: What specifiers can use I to set the total number of integers that display when writing an output? I need to have a total of 7 characters, and my problem is that the number of characters before and after the decimal varies. I don't care about the number integers after the decimal as long as the total number of characters does not exceed 8.

SO....

123.4567890   >> 123.4567
1.234567890   >> 1.234567
-1234.567890  >> -1234.56 
1234567.890   >> 1234567.

Answer 1

[Walter Roberson]

There is no direct method, but you can use

T = sprintf('%.6f', TheNumber);
fprintf('%s', T(1:8));

Answer 2

[Image Analyst]

It seems dangerous to limit it to 8 digits for when you have more than 8 digits to the left of the decimal point, but you can do this:

m = [...
123.4567890   %>> 123.4567
1.234567890   %>> 1.234567
-1234.567890  %>> -1234.56 
1234567.890   %>> 1234567.
123456789123] % DANGER - WILL CHOP OFF DIGITS!
% Convert numerical array to 2D character array.
s = num2str(m)
for row = 1 : size(s, 1)
  % Get just one row of s, trimming off blanks.
  oneRow = strtrim(s(row, :));
  % Get length.
  lastIndex = min(length(oneRow), 8);
  % Assign up to 8 characters max.
  s_8_columns_Only{row} = oneRow(1:lastIndex);
end
% Print out to command window:
celldisp(s_8_columns_Only)

[Walter Roberson]

The %.6f format I used is a bit of a trick: it handles the case of all of the useful information being to the right of the decimal, following '0' and '.', and it will 0 pad to the right to make 6 characters after the decimal, for a total of 8 minimum. Then since the length is always at least 8, I do not need to test the length and can instead just take the first 8 characters of the output. Simplifies the code.

[Image Analyst]

Yes, clever and simpler. Though both our methods limit output to 8 characters and he should be aware of that, though maybe he doesn't need to if he knows for a fact that there will be no number greater than 99999999.9