How can I print multiple text blocks containing numerical values of a matrix with the fprintf command?

Dear all,

I'm trying to write blocks of multiple text lines to a single text file by putting one block under the other. A single block needs to contain the following text and numerical values:

CASE i

NAME "Point load i"

NODAL

a FORCE 4 1.00000E+00

b FORCE 4 1.00000E+00

c FORCE 4 1.00000E+00

d FORCE 4 1.00000E+00

e FORCE 4 1.00000E+00

in which i needs to vary from 2 to 500, and the first column with node IDs (a b c d e representing integers) also changes from case to case.

In a first step I've put the case/name numbers in a 499x1-column vector and the node IDs in a 5x499-matrix:

N_l = 500; 

N_t = 5;                                       

NodeID = zeros(N_t,N_l-1);

NodeID(1,1) = 26;

NodeID(2,1) = 27;

NodeID(3,1) = 36;

NodeID(4,1) = 41;

NodeID(5,1) = 46;

for i = 1:N_t

      for j = 2:N_l-1

          NodeID(i,j) = NodeID(i,1) + (j-1)*25; 

      end

end

In the second step I tried to print the first three lines of the text block by using the following command lines:

    Case = 2:1:N_l;

    formatSpec = 'CASE %d\nNAME "Point load %d"\nNODAL\n';

    fprintf(formatSpec,Case)

fileID = fopen('data.txt','w');

fprintf(fileID,'CASE %d\r\nNAME "Point load %d"\r\nNODAL\r\n',Case);

fclose(fileID);

However, Matlab returns the following text:

CASE 2

NAME "Point load 3"

NODAL

CASE 4

NAME "Point load 5"

NODAL

CASE 6

NAME "Point load 7"

...

The numbering of the case and point load seems to be wrong. Moreover, I don't know how to print the second part of text lines within the same text block. Is this still possible with the fprintf command?

Kind regards,

Jeremy

[Stephen23]

Please

do

not

put

a

blank

line

between

every

line

of

your

code.

The code formatting works just fine without this. There is no need to make your life and our lives more difficult.

Answer 1

[Stephen23]

The way you are creating NodeID is very inefficient: learn about code vectorization to avoid this. Here it is using a much faster and neater bsxfun call:

D = 25;
N = 500;
X = [26,27,36,41,46];
Y = D*(0:N-1)';
NodeID = bsxfun(@plus,X,Y);

And then printing to file, perhaps something like this:

fid = fopen('temp.txt','wt');
for k = 2:N
    vec = +('a':'e'); % integers that can change between cases
    fprintf(fid,'CASE %d\nNAME "Point load %d"\nNODAL\n',k,k);
    fprintf(fid,'%c FORCE 4 %.5E\n',[vec;NodeID(k,:)]);
end
fclose(fid);

Which generates this file (obviously this is the first few lines only):

CASE 2
NAME "Point load 2"
NODAL
a FORCE 4 5.26000E+02
b FORCE 4 5.27000E+02
c FORCE 4 5.36000E+02
d FORCE 4 5.41000E+02
e FORCE 4 5.46000E+02
CASE 3
NAME "Point load 3"
NODAL
a FORCE 4 1.02600E+03
b FORCE 4 1.02700E+03
c FORCE 4 1.03600E+03
... ETC

You do not indicate what values should get printed in the blocks, so I assumed that these should be the NodeID values.

[Stephen23]

Based on your comment, this might do what you are after:

D = 25;
N = 500;
X = [26,27,36,41,46];
Y = D*(0:N-1)';
NodeID = bsxfun(@plus,X,Y);
%
vec = ones(1,5);
fid = fopen('temp.txt','wt');
for k = 1:size(NodeID,1)
    fprintf(fid,'CASE %d\nNAME "Point load %d"\nNODAL\n',1+k,1+k);
    fprintf(fid,'%d FORCE 4 %.5E\n',[NodeID(k,:);vec]);
end
fclose(fid);

And it generates this file:

CASE 2
NAME "Point load 2"
NODAL
26 FORCE 4 1.00000E+00
27 FORCE 4 1.00000E+00
36 FORCE 4 1.00000E+00
41 FORCE 4 1.00000E+00
46 FORCE 4 1.00000E+00
CASE 3
NAME "Point load 3"
NODAL
51 FORCE 4 1.00000E+00
52 FORCE 4 1.00000E+00
61 FORCE 4 1.00000E+00
66 FORCE 4 1.00000E+00
... ETC

But if you do not require the variable NodeID for any other calculations, then we can simplify even more by not defining it at all:

D = 25;
N = 500;
X = [26,27,36,41,46];
vec = ones(1,5);
fid = fopen('temp.txt','wt');
for k = 2:N
    fprintf(fid,'CASE %d\nNAME "Point load %d"\nNODAL\n',k,k);
    fprintf(fid,'%d FORCE 4 %.5E\n',[X+25*(k-2);vec]);
end

creates exactly the same file.