Loop for issue in me script

Hi, i need help with my loop for. I can't make it work if some one can help me

clear;
clc;
A=[1 0 0 -1 0 0; 1 0 0 0 0 0; 0 1 0 0 -1 0; 0 3 0 0 -1 -1; 0 0 1 0 0 -2; 0 -1 1 -2 0 0];
n=1;
for i=1
    B=[0; i; 0; 4*i; 0; -2*i];
    D=A\B;
    a1=D(1,:);
    b1=D(2,:);
    c1=D(3,:);
    d1=D(4,:);
    f1=D(5,:);
    g1=D(6,:);
    ae=a1-round(a1);
    be=b1-round(b1);
    ce=c1-round(c1);
    de=d1-round(d1);
    fe=f1-round(f1);
    ge=g1-round(g1);
    if ae==0 && be==0 && ce==0 && de==0 && fe==0 && ge==0 
        e=i;
        break;
    else
        i=i+1;
    end 
end
fprintf('a=%f b=%f c=%f d=%f e=%f f=%f g=%f',a1,b1,c1,d1,i,f1,g1);

a=1.000000 b=2.666667 c=2.666667 d=1.000000 e=2.000000 f=2.666667 g=1.333333

fprintf('\n a=%f b=%f c=%f d=%f e=%f f=%f g=%f',ae,be,ce,de,i,fe,ge);

 a=0.000000 b=-0.333333 c=-0.333333 d=0.000000 e=2.000000 f=-0.333333 g=0.333333

[Matt J]

It seems to run to completion without error messages, judging from the output in your post.

[Xavier Fleury]

maybe it's not my loop then, because I want all my values ​​of a, b,... to be integers

Answer 1

[Matt J]

clear;
clc;
A=[1 0 0 -1 0 0; 1 0 0 0 0 0; 0 1 0 0 -1 0; 0 3 0 0 -1 -1; 0 0 1 0 0 -2; 0 -1 1 -2 0 0];

i=1;
while 1
    B=[0; i; 0; 4*i; 0; -2*i];
    D=A\B;

    if all(  abs(D-round(D)) <  1e-8)
        e=i;
        break;
    else
        i=i+1;
    end 
    
end

    a1=D(1,:);
    b1=D(2,:);
    c1=D(3,:);
    d1=D(4,:);
    f1=D(5,:);
    g1=D(6,:);
    ae=a1-round(a1);
    be=b1-round(b1);
    ce=c1-round(c1);
    de=d1-round(d1);
    fe=f1-round(f1);
    ge=g1-round(g1);
e,

e = 3

fprintf('a=%f b=%f c=%f d=%f e=%f f=%f g=%f',a1,b1,c1,d1,i,f1,g1);

a=3.000000 b=8.000000 c=8.000000 d=3.000000 e=3.000000 f=8.000000 g=4.000000

fprintf('\n a=%f b=%f c=%f d=%f e=%f f=%f g=%f',ae,be,ce,de,i,fe,ge);

 a=0.000000 b=0.000000 c=0.000000 d=0.000000 e=3.000000 f=-0.000000 g=0.000000

[Xavier Fleury]

that's exaclty what i want thanks a lot but can you explain me what the ligne if does i don't understand

[Matt J]

that's exaclty what i want thanks a lot

You're welcome, but please Accept-click the answer to indicate that.

but can you explain me what the ligne if does i don't understand

Yes, if you tell me which line(s) you don't understand, I will explain them.

[Xavier Fleury]

the line 8 the "if"

[Matt J]

That line tests if all D(i) are nearly integers (within 1e-8). The all(tf) command will test if all elements of tf are true.

Note that you cannot expect D to be exactly integer-valued, because it is the result of floating point computations.

[Xavier Fleury]

Nice thanks a lot for your help.