How to find unknown in the equation

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Moza Mohamed
Moza Mohamed 2021-3-24
评论： Star Strider 2021-3-24
How to find w in equation 2. Below is my code i dont know what seems to be the problem.
a=4.3*10.^-3
r=1.68*10.^-8
t=[0:100:1083]
p=r.*[1+a.*(t-20)]
c=0.385
figure
syms w
sol = solve(r.*(1+(a./c).*w)==p) % equation 2
vpa( sol )

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采纳的回答

Star Strider
Star Strider 2021-3-24
Since ‘p’ is a vector, probably the easiest way to do this is to use a loop:
for k = 1:numel(p)
sol(k) = vpasolve(r.*(1+(a./c).*w)==p(k)) % equation 2
end
Thagt gives 11 values for ‘‘w’.
  2 个评论
Moza Mohamed
Moza Mohamed 2021-3-24
Thank you very much !!! I have another problem when trying to plot the values a figure is generated but without lines
for k = 1:numel(p)
sol = vpasolve(r.*(1+(a./c).*w)==p(k)) % equation 2
end
figure
plot(p,sol, "-b")
Star Strider
Star Strider 2021-3-24
Since ‘w’ is a funciton of ‘p’ and ‘sol’ is ‘w’, try this:
for k = 1:numel(p)
sol(k) = vpasolve(r.*(1+(a./c).*w)==p(k)); % equation 2
end
figure
plot(double(p), double(sol))
grid
xlabel('p')
ylabel('w')
The double calls are necessary in order to create the appropriate class of variables for plot.

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