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July 19th, 2017, 09:50 AM   #1
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Question 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.
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July 19th, 2017, 09:56 AM   #2
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Simpson's rule ?
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July 19th, 2017, 10:39 AM   #3
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Quote:
Originally Posted by Bl1nkPT View Post
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.
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July 19th, 2017, 10:40 AM   #4
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Quote:
Originally Posted by studiot View Post
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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