Math operations incorrect GUIDE

Question

qiana curcuru 2018-2-24

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/384518-math-operations-incorrect-guide

回答： Rik 2018-2-24

I am trying to draw a rectangle that has a width (lx) and length (ly) defined by user input with an edit text field using GUIDE. For some reason, the rectangle is not drawing correctly. Below I have the variables and corresponding values where X(1) and Y(1) is the location of the user's mouse click. For some reason, even though lx prints as the correct value, 2, when used in the equation X(1)-lx, lx suddenly becomes 50 and I have no idea why.

      disp(lx)
      disp(X(1))
      disp(X(1)-lx)
      disp(X(1)+lx)
     2
     299
     249
     349

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Answer 1

Rik 2018-2-24

1
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https://ww2.mathworks.cn/matlabcentral/answers/384518-math-operations-incorrect-guide#answer_306874

disp is hiding the fact that lx actually contains a char. If you do double('2') you will see the result is 50. To fix you calculations, use something like str2double.