unable to solve sybolically.

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jad kozah
jad kozah 2019-3-25
回答： jad kozah 2019-3-25
I'm trying to solve this equation but the software keeps on giving me this warning : unable to solve sybolically.
And it goes to vpasolve giving me one solution for x and y while i expecting 6 solutions for x and 6 for y.
when i reduce my equation to
psi = 20.*((y.*cosd(-30))-(x.*sind(-30))) + (c.*log (sqrt((x-1).^2 + (y-1).^2))) + (c.*log (sqrt((x-3).^2 + (y-2).^2)))
Matlab will solve it with no problem giving me two soltions for each x and y as expected.
Any help to solve the entire equation and get my 6 solutions for each x and y ?

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回答（2 个）

Krishna Kumar
Krishna Kumar 2019-3-25
Why do you declare this?- [x,y] = meshgrid(0:0.5:10, 0:0.5:10);
if you are anyway declaring x and y to be symbolic later. This could be a source of problem.
  2 个评论
jad kozah
jad kozah 2019-3-25
Thank you for your answer .
I tried to remove it .
i'm still getting the same error .
Any help ?
Krishna Kumar
Krishna Kumar 2019-3-25
Probably the use of sol=solve(u,v); i.e. the syntax could be an issue. I understand this solves u=0 for the variable v. Is this what you want? or do you want to solve psi=0 for x and y?

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jad kozah
jad kozah 2019-3-25
u is the derivative of psi with respect to y and v is the negative derivative of psi with respect to x.
so we will get u and v in function of x and y only.
u =
10*3^(1/2) + (1791925356007081*(2*y - 2))/(281474976710656*((x - 1)^2 + (y - 1)^2)) + (1791925356007081*(2*y - 4))/(281474976710656*((x - 3)^2 + (y - 2)^2)) + (1791925356007081*(2*y - 2))/(281474976710656*((x - 8)^2 + (y - 1)^2)) + (1791925356007081*(2*y - 4))/(281474976710656*((x - 6)^2 + (y - 2)^2)) + (1791925356007081*(2*y - 6))/(281474976710656*((x - 3)^2 + (y - 3)^2)) + (1791925356007081*(2*y - 6))/(281474976710656*((x - 6)^2 + (y - 3)^2))
v =
- (1791925356007081*(2*x - 2))/(281474976710656*((x - 1)^2 + (y - 1)^2)) - (1791925356007081*(2*x - 6))/(281474976710656*((x - 3)^2 + (y - 2)^2)) - (1791925356007081*(2*x - 6))/(281474976710656*((x - 3)^2 + (y - 3)^2)) - (1791925356007081*(2*x - 12))/(281474976710656*((x - 6)^2 + (y - 2)^2)) - (1791925356007081*(2*x - 12))/(281474976710656*((x - 6)^2 + (y - 3)^2)) - (1791925356007081*(2*x - 16))/(281474976710656*((x - 8)^2 + (y - 1)^2)) - 10
Then i want to get the unknows ( x and y )for u=0 and v=0
two equation ( u and v ) with two unknows ( x and y).
thank you in advanced

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