How to print in a text file?

I have to matrices x=[1;2;3] and U=[1 2 3; 4 5 6; 7 8 9].

I want to generate a .txt file of the name "output.txt" which would contain the following:

"

This is the output

x

1

2

3

U

1 2 3

4 5 6

7 8 9

"

How to do it?

Answer 1

[Ameer Hamza]

A slightly unusual way but it works

x=[1;2;3];
U=[1 2 3; 4 5 6; 7 8 9];

f = fopen('data.txt', 'w');
fprintf(f, 'This is the output\n');
fprintf(f, 'x\n');
writematrix(x, 'data.txt', 'WriteMode', 'append');
fseek(f, 0, 1);
fprintf(f, 'U\n');
writematrix(U, 'data.txt', 'WriteMode', 'append');
fclose(f);

[Ashesh Choudhury]

Thank you so much. What does the fseek do here?

[Ameer Hamza]

fseek(f, 0, 1); move the file pointer to the end of the file. You can try to run code after removing this line, and you can see the difference. For tab spacing, specify it in writematrix

x=[1;2;3];
U=[1 2 3; 4 5 6; 7 8 9];

f = fopen('data.txt', 'w');
fprintf(f, 'This is the output\n');
fprintf(f, 'x\n');
writematrix(x, 'data.txt', 'WriteMode', 'append', 'Delimiter', '\t');
fseek(f, 0, 1);
fprintf(f, 'U\n');
writematrix(U, 'data.txt', 'WriteMode', 'append', 'Delimiter', '\t');
fclose(f);

[Ashesh Choudhury]

Now, if I want to print another matrix with the previous two matrices, say V=[ 6 7 8; 1 2 3; 9 8 7], do I have to enter fseek(f, 0, 1) again?

The output should be:

"

This is the output

x

1

2

3

U

1 2 3

4 5 6

7 8 9

V

6 7 8

1 2 3

9 8 7

"

[Ameer Hamza]

Yes. It should be used again.

[Ashesh Choudhury]

Thank you very much :)

[Ashesh Choudhury]

Is there any way to control the number of digits after decimal that is being printed by writematrix?

[Ameer Hamza]

Not possible using writematrix, but you can use fprintf()

x=[1;2;3];
U=[1 2 3; 4 5 6; 7 8 9];
f = fopen('data.txt', 'w');
fprintf(f, 'This is the output\n');
fprintf(f, 'x\n');
fprintf(f, [repmat('%.2f', 1, size(x,2)) '\n'], x);
fprintf(f, 'U\n');
fprintf(f, [repmat('%.2f,', 1, size(U,2)) '\n'], U);
fclose(f);