MATLAB: Sprintf and minus sign problem

MATLABsprintf minus sign

I have a problem understanding the sprintf function in a specific case:

sprintf('%.2f', 0)

produces: "0.00" , as expected.

In my case I have a variable [value] that should equal 0:

value == 0
  ans = 1

but

sprintf(%.2f, value)

results in "-0.00" (a minus sign is added)

Is there any chance that [value] still contains something different from 0, eventhough value == 0 retuns TRUE?

Best Answer

MATLAB supports signed 0. See http://www.mathworks.com/matlabcentral/newsreader/view_thread/251089

Related Solutions

MATLAB: Does FPRINTF put minus signs in front of zeros in the file

This is a result of 0 and -0 having different IEEE representations. The following example MATLAB code illustrates this difference:

>> format hex
>> [0 -0]
 ans =
    0000000000000000   8000000000000000

When MATLAB calls FPRINTF, MATLAB actually calls a C routine which treats them differently. However, despite this difference, MATLAB treats 0 and -0 the same in all calculations (ie. 0 == -0). Therefore you can work around this behavior by replacing '-0' with 0 in MATLAB, as shown in the following example:

m = [0 -0]
fprintf(1,'m = [%1.2f %1.2f]\n',m)
m(m==0) = 0
fprintf(1,'m = [%1.2f %1.2f]\n',m)
 m =
      0     0
 m = [0.00 -0.00]
 m =
      0     0
 m = [0.00 0.00]

MATLAB: “plus/minus” sign operator

It depends what you want to do with it.

M = [1 1 1; 1 1 -1; 1 -1 1; 1 -1 -1; -1 1 1; -1 1 -1; -1 -1 1; -1 -1 -1];

Out = (M * Row')' ;

Each row of Out is what you want.

You might want to programatically generate M if you have more columns on your row.

Best Answer

Related Solutions

MATLAB: Does FPRINTF put minus signs in front of zeros in the file

MATLAB: “plus/minus” sign operator

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