[faysaal]

Hi all..
I am doing my Masters Thesis in CFD. I have to write a code in Matlab first to generate an algebraic grid (which I have done) and then solve Euler Equation using Runge-Kutta method with TVD.

The ramp which I have to solve contains a compression corner followed by an expansion corner.

The problem which I have in Matlab is reading files into arrays.In Fortran we would see use the read/write statement simply as, for WRITING

OPEN(1,FILE=GRID.DAT)
WRITE(*,*) 'READING GRID ...'
DO 110 J=1,JM
DO 120 I=1,IM
WRITE(1,104)X(I,J),Y(I,J),XIX(I,J),XIY(I,J),
& ETAX(I,J),ETAY(I,J),JJ(I,J)
120 CONTINUE
110 CONTINUE
104 FORMAT(7(2X,D14.8))
CLOSE(1)

and for READING

OPEN(1,FILE=GRID.DAT)
WRITE(*,*) 'READING GRID ...'
DO 110 J=1,JM
DO 120 I=1,IM
READ (1,104)X(I,J),Y(I,J),XIX(I,J),XIY(I,J),
& ETAX(I,J),ETAY(I,J),JJ(I,J)
120 CONTINUE
110 CONTINUE
104 FORMAT(7(2X,D14.8))
CLOSE(1)


can someone please tell me how this can be done in Matlab?

[FMDenaro]

load "file.dat" - ascii

is an example to read data in matlab, they will be stored in the array file.


yc = [x(1:n); y(1:n)];fid = fopen('y_x.dat','w');
fprintf(fid,'%7.4f %12.8f\n',yc); fclose(fid);

is an example of writing the vectors y and x on the file y_x.dat

[faysaal]

Thanks..I will give it a try and come back

[faysaal]

I have written the data in this fashion

fid = fopen('grid.txt','w');
for J=1:JM
for I=1:IM
fprintf (fid,'%12.6f%12.6f%12.6f%12.6f%12.6f%12.6f%12.6f\n ',X(I,J),Y(I,J),XIX(I,J),XIY(I,J),ETAX(I,J),ETAY(I ,J),JJ(I,J));
end
end

fclose(fid);
end

Now I want the same to be read accordingly. I will attach grid.txt for your reference that is generated by the above code. Thanks for the help.

[LuckyTran]

If you wrote it using fprintf the easiest way is to read it using fscanf the same way.

Another way could be to use textscan, but I think fscanf is the most straightforward.

[faysaal]

I am trying to solve it but there is an error which say's "sub-scripted assignment mismatch". Here is the code for reading the first array X(I,J) that is the first column of grid.txt which contains seven columns each belonging to the seven arrays.

for J=1:131
for I=1:241
X(I,J)=fscanf(fid,'%f/n',1);
end
end

I want fscanf to allocate the first value(first row first column) of grid.txt to X(1,1). The second value(second row first coulmn) to X(2,1), the third to X(3,1) and so on up till (IMth row and first column,assuming IM as a finite integer) X(IM,1). After that X(1,2),X(2,2),X(3,2)...X(IM,2),X(1,3),X(2,3)...X(I M,3)......X(IM,JM).

[kaya]

Originally Posted by faysaal

I am trying to solve it but there is an error which say's "sub-scripted assignment mismatch". Here is the code for reading the first array X(I,J) that is the first column of grid.txt which contains seven columns each belonging to the seven arrays.

for J=1:131
for I=1:241
X(I,J)=fscanf(fid,'%f/n',1);
end
end

I want fscanf to allocate the first value(first row first column) of grid.txt to X(1,1). The second value(second row first coulmn) to X(2,1), the third to X(3,1) and so on up till (IMth row and first column,assuming IM as a finite integer) X(IM,1). After that X(1,2),X(2,2),X(3,2)...X(IM,2),X(1,3),X(2,3)...X(I M,3)......X(IM,JM).

fid = fopen('grid.txt','r');
for J=1:JM
for I=1:IM
buffer=fscanf(fid,[repmat('%f',1,7) '/n'])
X(IM,JM)=buffer(1);
Y(IM,JM)=buffer(2);
XIX(IM,JM)=buffer(3);
XIY(IM,JM)=buffer(4);
ETAX(IM,JM)=buffer(5);
ETAY(IM,JM)=buffer(6);
JJ(IM,JM)=buffer(7);
end
end
fclose(fid);

[faysaal]

Originally Posted by kaya

fid = fopen('grid.txt','r');
for J=1:JM
for I=1:IM
buffer=fscanf(fid,[repmat('%f',1,7) '/n'])
X(IM,JM)=buffer(1);
Y(IM,JM)=buffer(2);
XIX(IM,JM)=buffer(3);
XIY(IM,JM)=buffer(4);
ETAX(IM,JM)=buffer(5);
ETAY(IM,JM)=buffer(6);
JJ(IM,JM)=buffer(7);
end
end
fclose(fid);

Thanks a lot Kaya it worked like a charm by only changing (IM,JM) to (I,J) Finally i got what I needed after so many days. Thanks once again.