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 July 19th, 2017, 09:50 AM #1 Newbie   Joined: Jul 2017 From: Portugal, Lisbon Posts: 2 Thanks: 0 Help with boundary conditions Hey, I need help with the resolution of a problem. So the situation is this. I am defining a polynomial line that represents the areas of the sections of a ship hull. (area at each section is a value for y and x the location of said section). I don't have all the sections area. I have 10 boundary conditions. This equals a 9th order polinomy. the 8th and 9th boundary conditions have integrals, as to control the volume of the ship. I don't have any idea about the coeficients of the polinomy (A0,...,A9) So what i have is: y=A9.x^9+....+A0 for my calculations I'm only using the matrix of X, example for x=1, y=0 A(1,: )=[1 1 1 1 1 1 1 1 1 1] B(1)=0 The problem arrives when the boundary is defined as: integral(y dx,-1,x1)+L*1+integral(y dx, x2, 1)=2*Cp where L and Cp are cosntants given by me. How do I solve this integrals if I don't have the coefficients? Thanks guys Last edited by Bl1nkPT; July 19th, 2017 at 09:54 AM.
 July 19th, 2017, 09:56 AM #2 Senior Member   Joined: Jun 2015 From: England Posts: 915 Thanks: 271 Simpson's rule ?
July 19th, 2017, 10:39 AM   #3
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Quote:
 Originally Posted by Bl1nkPT Hey, I need help with the resolution of a problem. So the situation is this. I am defining a polynomial line that represents the areas of the sections of a ship hull. (area at each section is a value for y and x the location of said section). I don't have all the sections area. I have 10 boundary conditions. This equals a 9th order polinomy. the 8th and 9th boundary conditions have integrals, as to control the volume of the ship. I don't have any idea about the coeficients of the polinomy (A0,...,A9) So what i have is: y=A9.x^9+....+A0 for my calculations I'm only using the matrix of X, example for x=1, y=0 A(1,: )=[1 1 1 1 1 1 1 1 1 1] B(1)=0 The problem arrives when the boundary is defined as: integral(y dx,-1,x1)+L*1+integral(y dx, x2, 1)=2*Cp where L and Cp are cosntants given by me. How do I solve this integrals if I don't have the coefficients? Thanks guys
Just solve it formula keeping the coefficients of the integral as unkown. You'll end up with a linear equation in the coefficients.

July 19th, 2017, 10:40 AM   #4
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Joined: Jul 2017
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Quote:
 Originally Posted by studiot Simpson's rule ?
That gives me the result of the integral, I need it in xx-matrix form in order to get the coefficients.

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