Subtraction of negative matrix element

Question

Michael 2018-8-12

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/414567-subtraction-of-negative-matrix-element

评论： Michael 2018-8-15

Hello

My data (X,Y) and I am trying to find the distance between the Y value of two points. My issue results from the negative Y value of one of the points. Concept A =1; B =-3; C= A-B; -->4 However, I keep getting an error message

% line 1 has the following values
0  0.750000000000000
0  0
0  -0.500000000000000
0  -0.750000000000000
% Subtraction method
DistX2 = minus(line1 (1,2), line (3,2)); 
DistX2 = (line1 (1,2) - line (3,2)); 
% error code
Undefined operator '-' for input arguments of type 'matlab.graphics.primitive.Line'.
Error in PlotCurve (line 50)
DistX2 = minus(line1 (1,2), line (3,2));

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Stephen23 2018-8-12

编辑：Stephen23 2018-8-12

@Michael: a line object is not a numeric array. They cannot be "subtracted" in any meaningful way. You could get the Ydata values and subtract those. But most likely it would be simpler and easier to just subtract the values that you used to create the line object: so how did you create this line object?

Do NOT call your variable line, as this shadows the very important inbuilt line function.

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Answer 1

Image Analyst 2018-8-12

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/414567-subtraction-of-negative-matrix-element#answer_332491

line() is a built-in function and you are not using it correctly. Do not use built-in function names for names of your variables. Call it line2 or something instead of line.