MATLAB: Not effective validation algorithm for input format

checkisnumericMATLABnumericstring

Hello everyone, I am asking as input, coordinates of quadrilateral vertices and I am adding an extra layer for format checking. Simply speaking inputs must be numerical.
vx=zeros(1,4);
vy=zeros(1,4);
vertices=['A'; 'B'; 'C'; 'D'];
fprintf('\nPlease enter the coordinates of vertices:\n');
for cnt=1:4
    fprintf('\n For vertix <strong> %s </strong>', vertices(cnt));
    fprintf(' :\n');
    vx(cnt) = input('  Χ=');
    vxtest=isnumeric(vx(cnt));
    while vxtest==0
        fprintf('ERROR: Non numerical character, try again.\n');
        vx(cnt) = input('  Χ=');
        vxtest=isnumeric(vx(cnt));
    end
    vy(cnt) = input('  Y=');
    vytest=isnumeric(vy(cnt));
    while vytest==0
        fprintf('ERROR: Non numerical character, try again.\n');
        vy(cnt) = input('  Y=');
        vytest=isnumeric(vy(cnt));
    end
end
vx=vx(1:4);
vy=vy(1:4);
But still it is possible to put a string as an input and continue to the next coordinate. At the end, there is an output area of a quadrilateral with vertices out of string coordinates.
Thanks in advance!

Best Answer

Try this
vx=zeros(1,4);
vy=zeros(1,4);
vertices=['A'; 'B'; 'C'; 'D'];
fprintf('\nPlease enter the coordinates of vertices:\n');
for cnt=1:4
    fprintf('\n For vertix <strong> %s </strong>', vertices(cnt));
    fprintf(' :\n');
    temp = input('  Χ=');
    vxtest=isnumeric(temp);
    vx(cnt) = temp;
    while vxtest==0
        fprintf('ERROR: Non numerical character, try again.\n');
        temp = input('  Χ=');
        vxtest=isnumeric(temp);
        vx(cnt) = temp;
    end
    temp = input('  Y=');
    vytest=isnumeric(temp);
    vy(cnt) = temp;
    while vytest==0
        fprintf('ERROR: Non numerical character, try again.\n');
        temp = input('  Y=');
        vytest=isnumeric(temp);
        vy(cnt) = temp;
    end
end
vx=vx(1:4);
vy=vy(1:4);
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