calculations with respect to row vectors

Dear Sir:

I was using an old version of matlab (I believe matlab 6) at school.

Can you please tell me why matlab is returning data that appears to be in error?

Please examine the *.m code that I have copied and pasted below (delete or insert the semicolon symbol ; to see the values output by matlab):

%Example:

t=[0:5]  % t =  [ 0     1     2     3     4     5 ]

t=[0:5]/5 % t =  [ 0    0.2000    0.4000    0.6000    0.8000    1.0000 ]
% so far, so good everything is logical and rational

% The problem is set forth in the next line below:

t = [0:16383]/125000000 % Column 16384 = 0.13106400000000;  This value is not logical 

% Verification that a mathematical anomoly is present:

a=16383/125000000 % matlab returns:  a = 1.310640000000000e-004

Can you tell me why matlab is returning this value? Also, try this equation below and the anomaly will repeat itself.

b=16383/125000000000;

Answer 1

[Star Strider]

It probably has to do with the existing format:

format long
t = [0:1638:16383]/125000000 

t =
   1.0e-03 *
  Columns 1 through 4
                   0   0.013104000000000   0.026208000000000   0.039312000000000
  Columns 5 through 8
   0.052416000000000   0.065520000000000   0.078624000000000   0.091728000000000
  Columns 9 through 11
   0.104832000000000   0.117936000000000   0.131040000000000

Note that the display of the vector (that I shortened for convenience) is preceded by ‘1.0e-03 *’ indicating that the entire vector is to be multiplied by 1e-03.

So there is no error. You likely didn’t see the common multiplier (displayed at the beginning of the output) when you output the very long, 16384-element vector, because it scrolled off the top of the Command Window before you could see it. Shortening the vector for illustration purposes displays it.

[loginID00]

Thank you for your most excellent answer.

When I was using the program and I scrolled upward, matlab stopped my scroll upward.

Can you please tell me how I can view the output from the beginning where the number and * operation, 1.0e-03 *, begins?

Again, I would like to thank you for your answer.

[Star Strider]

My pleasure.

Only a part of the Command Window will ever be visible, so with a long output, the beginning will scroll off the top of the Command Window, and you cannot scroll up to it.

You can save the output displayed in the Command Window to a file with the diary function, so you can see all of it in a text file. (See the documentation for diary for details.)

The best way to thank me is to Accept my Answer.

[loginID00]

I think the best way to solve this problem may be to pose this question:

Do you know a way I can configure the command window outputs so that I always return a simple, numeric, whereby the complete answer is contained in every vector/array entry?

[Star Strider]

I would use fprintf (or sprintf) to do that. See the documentation and the variety of format descriptors (such as '%f', '%E', and the rest) for details. You will have to experiment to get the result you want.