Viscosity Solution for Hamilton Jacobi equation












1












$begingroup$


I am trying to do a numerical approximation of the viscosity solution for the Hamilton-Jacobi problem



$hspace{5cm}displaystyle frac{du}{dt}+frac{|u_x|^2}{2}=0 hspace{0.5cm} x in mathbb{R},hspace{0.3cm}t in [0,+infty[$



$hspace{5cm}displaystyle u(x,0)=sin(x)hspace{0.5cm}x in mathbb{R}$



So I need to calculate the explicit solution to compare them. I read about Lax-Hopf formula applied to the general problem and the solution should be



$$u(x,t)=inf_{y in mathbb{R}} left { sin(y)+frac{|x-y|^2}{2t}right }$$



Can someone give me some help/ hint to find a explicit form for this infimus? Greetings










share|cite|improve this question











$endgroup$












  • $begingroup$
    The minimum is attained when $$cos(y) + (y-x)/t=0.$$ Such equations generally can not be solved explicitly. You might try the method of characteristics.
    $endgroup$
    – Jeff
    Oct 11 '17 at 15:00












  • $begingroup$
    I should add, you can always compute the inf using a root finding algorithm, like Newton's method, up to machine accuracy to compare your numerical solution against.
    $endgroup$
    – Jeff
    Oct 11 '17 at 15:02










  • $begingroup$
    Thx, ill try to compute this.
    $endgroup$
    – Mat128
    Oct 12 '17 at 9:14
















1












$begingroup$


I am trying to do a numerical approximation of the viscosity solution for the Hamilton-Jacobi problem



$hspace{5cm}displaystyle frac{du}{dt}+frac{|u_x|^2}{2}=0 hspace{0.5cm} x in mathbb{R},hspace{0.3cm}t in [0,+infty[$



$hspace{5cm}displaystyle u(x,0)=sin(x)hspace{0.5cm}x in mathbb{R}$



So I need to calculate the explicit solution to compare them. I read about Lax-Hopf formula applied to the general problem and the solution should be



$$u(x,t)=inf_{y in mathbb{R}} left { sin(y)+frac{|x-y|^2}{2t}right }$$



Can someone give me some help/ hint to find a explicit form for this infimus? Greetings










share|cite|improve this question











$endgroup$












  • $begingroup$
    The minimum is attained when $$cos(y) + (y-x)/t=0.$$ Such equations generally can not be solved explicitly. You might try the method of characteristics.
    $endgroup$
    – Jeff
    Oct 11 '17 at 15:00












  • $begingroup$
    I should add, you can always compute the inf using a root finding algorithm, like Newton's method, up to machine accuracy to compare your numerical solution against.
    $endgroup$
    – Jeff
    Oct 11 '17 at 15:02










  • $begingroup$
    Thx, ill try to compute this.
    $endgroup$
    – Mat128
    Oct 12 '17 at 9:14














1












1








1


1



$begingroup$


I am trying to do a numerical approximation of the viscosity solution for the Hamilton-Jacobi problem



$hspace{5cm}displaystyle frac{du}{dt}+frac{|u_x|^2}{2}=0 hspace{0.5cm} x in mathbb{R},hspace{0.3cm}t in [0,+infty[$



$hspace{5cm}displaystyle u(x,0)=sin(x)hspace{0.5cm}x in mathbb{R}$



So I need to calculate the explicit solution to compare them. I read about Lax-Hopf formula applied to the general problem and the solution should be



$$u(x,t)=inf_{y in mathbb{R}} left { sin(y)+frac{|x-y|^2}{2t}right }$$



Can someone give me some help/ hint to find a explicit form for this infimus? Greetings










share|cite|improve this question











$endgroup$




I am trying to do a numerical approximation of the viscosity solution for the Hamilton-Jacobi problem



$hspace{5cm}displaystyle frac{du}{dt}+frac{|u_x|^2}{2}=0 hspace{0.5cm} x in mathbb{R},hspace{0.3cm}t in [0,+infty[$



$hspace{5cm}displaystyle u(x,0)=sin(x)hspace{0.5cm}x in mathbb{R}$



So I need to calculate the explicit solution to compare them. I read about Lax-Hopf formula applied to the general problem and the solution should be



$$u(x,t)=inf_{y in mathbb{R}} left { sin(y)+frac{|x-y|^2}{2t}right }$$



Can someone give me some help/ hint to find a explicit form for this infimus? Greetings







pde hamilton-jacobi-equation viscosity-solutions






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 11 '18 at 11:36









Harry49

7,26831240




7,26831240










asked Oct 9 '17 at 9:23









Mat128Mat128

1204




1204












  • $begingroup$
    The minimum is attained when $$cos(y) + (y-x)/t=0.$$ Such equations generally can not be solved explicitly. You might try the method of characteristics.
    $endgroup$
    – Jeff
    Oct 11 '17 at 15:00












  • $begingroup$
    I should add, you can always compute the inf using a root finding algorithm, like Newton's method, up to machine accuracy to compare your numerical solution against.
    $endgroup$
    – Jeff
    Oct 11 '17 at 15:02










  • $begingroup$
    Thx, ill try to compute this.
    $endgroup$
    – Mat128
    Oct 12 '17 at 9:14


















  • $begingroup$
    The minimum is attained when $$cos(y) + (y-x)/t=0.$$ Such equations generally can not be solved explicitly. You might try the method of characteristics.
    $endgroup$
    – Jeff
    Oct 11 '17 at 15:00












  • $begingroup$
    I should add, you can always compute the inf using a root finding algorithm, like Newton's method, up to machine accuracy to compare your numerical solution against.
    $endgroup$
    – Jeff
    Oct 11 '17 at 15:02










  • $begingroup$
    Thx, ill try to compute this.
    $endgroup$
    – Mat128
    Oct 12 '17 at 9:14
















$begingroup$
The minimum is attained when $$cos(y) + (y-x)/t=0.$$ Such equations generally can not be solved explicitly. You might try the method of characteristics.
$endgroup$
– Jeff
Oct 11 '17 at 15:00






$begingroup$
The minimum is attained when $$cos(y) + (y-x)/t=0.$$ Such equations generally can not be solved explicitly. You might try the method of characteristics.
$endgroup$
– Jeff
Oct 11 '17 at 15:00














$begingroup$
I should add, you can always compute the inf using a root finding algorithm, like Newton's method, up to machine accuracy to compare your numerical solution against.
$endgroup$
– Jeff
Oct 11 '17 at 15:02




$begingroup$
I should add, you can always compute the inf using a root finding algorithm, like Newton's method, up to machine accuracy to compare your numerical solution against.
$endgroup$
– Jeff
Oct 11 '17 at 15:02












$begingroup$
Thx, ill try to compute this.
$endgroup$
– Mat128
Oct 12 '17 at 9:14




$begingroup$
Thx, ill try to compute this.
$endgroup$
– Mat128
Oct 12 '17 at 9:14










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