Integrating with a max function as denominator.












2












$begingroup$


I am trying to integrate forces over an area for a personal project of mine. I simplified and extracted the integrals that i could, but i ended with these:



$$0.5 int_0^1 frac{x}{max(x(P_{1y} - P_{2y}) + P_{2y} - w, 0) + h} dx$$
that i try to resolve in the form of:
$$ y = x(P_{1y} - P_{2y}) + P_{2y} - w $$
$$int_0^1 frac{x}{y(1 + sgn(y)) + 2h}dx$$
or
$$int_0^1 frac{x}{y + abs(y) + 2h}dx$$



I also have other integrals where there is $x^2$, $x^3$ and $x^4$ instead of $x$ the numerator.



$P$ being the two points of a segment (x is between 0 and 1 and represents the linear interpolation between the two)



$w, P in mathbb{R} $ and $h in mathbb{R_{>0}}$



That is clearly defined over $mathbb{R}$ and should have a fully defined result right?



But whatever i try i fall onto the derivative which isn't fully defined and yields odd results that make it unusable.



Integration over separate ranges could work, but the check for the intersection is $frac{w-P_{2y}}{P_{1y} - P_{2y}}$ and is undefined when the two points are on the same y position, and checking it would require more checks which i am trying to avoid because it is used on a GPU simulation and it would slow down things significantly.



What methods are there solve these beyond the basic integration by parts or by substitution? (this is a personal project so as long as it works even with magic i'm a taker)










share|cite|improve this question











$endgroup$

















    2












    $begingroup$


    I am trying to integrate forces over an area for a personal project of mine. I simplified and extracted the integrals that i could, but i ended with these:



    $$0.5 int_0^1 frac{x}{max(x(P_{1y} - P_{2y}) + P_{2y} - w, 0) + h} dx$$
    that i try to resolve in the form of:
    $$ y = x(P_{1y} - P_{2y}) + P_{2y} - w $$
    $$int_0^1 frac{x}{y(1 + sgn(y)) + 2h}dx$$
    or
    $$int_0^1 frac{x}{y + abs(y) + 2h}dx$$



    I also have other integrals where there is $x^2$, $x^3$ and $x^4$ instead of $x$ the numerator.



    $P$ being the two points of a segment (x is between 0 and 1 and represents the linear interpolation between the two)



    $w, P in mathbb{R} $ and $h in mathbb{R_{>0}}$



    That is clearly defined over $mathbb{R}$ and should have a fully defined result right?



    But whatever i try i fall onto the derivative which isn't fully defined and yields odd results that make it unusable.



    Integration over separate ranges could work, but the check for the intersection is $frac{w-P_{2y}}{P_{1y} - P_{2y}}$ and is undefined when the two points are on the same y position, and checking it would require more checks which i am trying to avoid because it is used on a GPU simulation and it would slow down things significantly.



    What methods are there solve these beyond the basic integration by parts or by substitution? (this is a personal project so as long as it works even with magic i'm a taker)










    share|cite|improve this question











    $endgroup$















      2












      2








      2


      1



      $begingroup$


      I am trying to integrate forces over an area for a personal project of mine. I simplified and extracted the integrals that i could, but i ended with these:



      $$0.5 int_0^1 frac{x}{max(x(P_{1y} - P_{2y}) + P_{2y} - w, 0) + h} dx$$
      that i try to resolve in the form of:
      $$ y = x(P_{1y} - P_{2y}) + P_{2y} - w $$
      $$int_0^1 frac{x}{y(1 + sgn(y)) + 2h}dx$$
      or
      $$int_0^1 frac{x}{y + abs(y) + 2h}dx$$



      I also have other integrals where there is $x^2$, $x^3$ and $x^4$ instead of $x$ the numerator.



      $P$ being the two points of a segment (x is between 0 and 1 and represents the linear interpolation between the two)



      $w, P in mathbb{R} $ and $h in mathbb{R_{>0}}$



      That is clearly defined over $mathbb{R}$ and should have a fully defined result right?



      But whatever i try i fall onto the derivative which isn't fully defined and yields odd results that make it unusable.



      Integration over separate ranges could work, but the check for the intersection is $frac{w-P_{2y}}{P_{1y} - P_{2y}}$ and is undefined when the two points are on the same y position, and checking it would require more checks which i am trying to avoid because it is used on a GPU simulation and it would slow down things significantly.



      What methods are there solve these beyond the basic integration by parts or by substitution? (this is a personal project so as long as it works even with magic i'm a taker)










      share|cite|improve this question











      $endgroup$




      I am trying to integrate forces over an area for a personal project of mine. I simplified and extracted the integrals that i could, but i ended with these:



      $$0.5 int_0^1 frac{x}{max(x(P_{1y} - P_{2y}) + P_{2y} - w, 0) + h} dx$$
      that i try to resolve in the form of:
      $$ y = x(P_{1y} - P_{2y}) + P_{2y} - w $$
      $$int_0^1 frac{x}{y(1 + sgn(y)) + 2h}dx$$
      or
      $$int_0^1 frac{x}{y + abs(y) + 2h}dx$$



      I also have other integrals where there is $x^2$, $x^3$ and $x^4$ instead of $x$ the numerator.



      $P$ being the two points of a segment (x is between 0 and 1 and represents the linear interpolation between the two)



      $w, P in mathbb{R} $ and $h in mathbb{R_{>0}}$



      That is clearly defined over $mathbb{R}$ and should have a fully defined result right?



      But whatever i try i fall onto the derivative which isn't fully defined and yields odd results that make it unusable.



      Integration over separate ranges could work, but the check for the intersection is $frac{w-P_{2y}}{P_{1y} - P_{2y}}$ and is undefined when the two points are on the same y position, and checking it would require more checks which i am trying to avoid because it is used on a GPU simulation and it would slow down things significantly.



      What methods are there solve these beyond the basic integration by parts or by substitution? (this is a personal project so as long as it works even with magic i'm a taker)







      definite-integrals






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      edited Jan 9 at 15:55







      Wicpar

















      asked Jan 9 at 0:35









      WicparWicpar

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