Help to Improve this short code (create a rect given initial point, final point and slope)

Question

Aaron Garcia 2020-5-30

0
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https://ww2.mathworks.cn/matlabcentral/answers/538167-help-to-improve-this-short-code-create-a-rect-given-initial-point-final-point-and-slope

评论： Aaron Garcia 2020-5-30

Hello there!!

I have write this code to find the Y values of a line, given two points and slope (calculate previous call the funtion), its to simple but in implementation i calling this function around 10 million times, so i need te reduce the time that it takes, if someone have some advice it would be helpful thank you!!!.

function[y] = LineFuntion(pts,m,Pi,Pf)
        y=zeros(1,pts);
        
         if abs(m) == Inf  % vertical line         
            y(1:pts) = linspace(Pi(2),Pf(2),pts);
         elseif m == 0 % horizontal  line        
            y(1:pts) = Pi(2);
         else 
            x=zeros(1,pts);
            x(1:pts) = linspace(Pi(1),Pf(1),pts); %this line is the most time consuming
            y(1:pts) = m*(x-Pi(1))+Pi(2);  %this line is the second most time consuming         
         end 
         
  end

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Answer 1

Mehmed Saad 2020-5-30

1
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https://ww2.mathworks.cn/matlabcentral/answers/538167-help-to-improve-this-short-code-create-a-rect-given-initial-point-final-point-and-slope#answer_442891

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function[y] = LineFuntion(pts,m,Pi,Pf)
       
         if abs(m) == Inf  % vertical line         
            y = linspace(Pi(2),Pf(2),pts);
         elseif m == 0 % horizontal  line        
            y = repmat(Pi(2),1,pts);
         else 
            x = linspace(Pi(1),Pf(1),pts);
            y = m*(x-Pi(1))+Pi(2);
         end 
         
  end