- #1
teknodude
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- 0
{\frac {{\it du}}{{\it dx}}}=998\,u+1998\,v
{\frac {{\it dv}}{{\it dx}}}=-999\,u-1999\,v
u \left( 0 \right) =1
v \left( 0 \right) =0
0<x<10
Second Order Backward Difference formula
{\frac {f_{{k-2}}-4\,f_{{k-1}}+3f_{{k}}}{h}}
I'm trying solve this numerically in matlab, but can't seem to figure out what to do with the k-2 indice in the 2nd order backward difference equation, because it is outside the boundary. I was thinking of using a ficticious or ghost point, but I thought that only applies if a neuman boundary condition is given. The way i think of it, I have 4 unknowns and only 2 equations.
EDIT: ok after thinking about it. I think I have to use another numerical method to start the process, like RK4.
{\frac {{\it dv}}{{\it dx}}}=-999\,u-1999\,v
u \left( 0 \right) =1
v \left( 0 \right) =0
0<x<10
Second Order Backward Difference formula
{\frac {f_{{k-2}}-4\,f_{{k-1}}+3f_{{k}}}{h}}
I'm trying solve this numerically in matlab, but can't seem to figure out what to do with the k-2 indice in the 2nd order backward difference equation, because it is outside the boundary. I was thinking of using a ficticious or ghost point, but I thought that only applies if a neuman boundary condition is given. The way i think of it, I have 4 unknowns and only 2 equations.
EDIT: ok after thinking about it. I think I have to use another numerical method to start the process, like RK4.
Last edited:
