Variable precision point for fprintf command set by user input

I am trying to create a variable precision point through an user input to control how many decimal places are shown when displaying the results from the elements of a matrix.

This code is what I current have but would like to make the precision (currently at 10) adjustable:

when I try to replace the .10 with * and set a variable it messes up my code:

I am new to Matlab and would appreciate any help on this so I can input a values to dispaly results to any decimal place value.

Answer 1

[Voss]

Here's what the documentation for fprintf has to say about this:

"When you specify * as the field precision operator, the other input arguments must provide both a precision and a value to be printed. Precisions and values can be pairs of arguments, or pairs within a numeric array."

So the precisions and values must be in pairs. Example:

M = [1 2 3 4; 5 6 7 8];
precision = 10;

[nrows,ncols] = size(M);

args = zeros(1,2*ncols);     % row vector of precision/value pairs
args(1:2:end) = precision;   % 1st, 3rd, 5th, etc., elements are the precisions

for ii = 1:nrows
    args(2:2:end) = M(ii,:); % 2nd, 4th, 6th, etc., elements are the values from M
    fprintf("   %10.*f",args)
    fprintf("\n")
end

   1.0000000000   2.0000000000   3.0000000000   4.0000000000

   5.0000000000   6.0000000000   7.0000000000   8.0000000000

[Nathan]

Thank you, that works perfectly

[Voss]

You're welcome!

Answer 2

[Walter Roberson]

fprintf( fprintf('   %%10.%df'), precision), Ab(i,:))

[Nathan]

I tried this code and keep getting alarm messages. I had to remove the parenthesis after %%10.%df') so it wouldn't alarm out at the start. I tried changing between %%10.%df', %%10.%ff', and %%10.*ff' and nothing is working.

[Walter Roberson]

fprintf( sprintf('   %%10.%df', precision), Ab(i,:))

[Nathan]

that worked perfectly as well. Thank you. I'll have to look into the code you created to understand the nesting and fprint/sprint command.

[Walter Roberson]

It is equivalent to

Format = sprintf('   %%10.%df', precision);
fprintf(Format, Ab(i,:));

The sprintf() computes the format to be used by the fprintf()