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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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 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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 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. Tags boundary, conditions, polinomy Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post Azzaz Differential Equations 0 November 20th, 2014 05:55 AM JWS Topology 5 May 26th, 2014 07:31 PM jacynty123 Calculus 0 May 21st, 2011 01:50 AM jakeward123 Physics 1 April 5th, 2011 08:22 AM nienawiedzony Real Analysis 24 May 9th, 2010 03:40 AM

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