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# Solve an equation not getting a result

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Hey here is my code, I don't know why I am not getting an answer,

E=9*10^3; nu=0.3; k=0.01; G=2*10^3; evide0=0.8;increment1=0.0001;

e1=[0:increment1:1];

s01=0;

s1=[s01];s1(1)=s01;

for i=2:length(e1)

syms x

a=double(solve(increment1==((1/3)*(k/(1+evide0))*((x-s1(i-1))/x))+((1/3*G)*(x-s1(i-1)))),x);

s1(i)=a

if s1(i)>500

s1=s1(1:(i-1));

break

end

end

I am not getting a value in a

##### 0 Comments

### Answers (2)

Star Strider
on 12 Feb 2022

The solve call was causing problems because the conversion and testing in the if block would then not work correctly because the logical test does not work for symbolic variables. Also, the ‘a’ result was frequently empty, and that effectively stopped the iteration. So I changed the call to fsolve (and made approprite changes to the code for the expression it was to solve) that elimnated those problems, and temporarily changed the value of ‘increment1’ to something reasonable that I could execute in the online Run feature here.

% syms x

E=9*10^3;

nu=0.3;

k=0.01;

G=2*10^3;

evide0=0.8;

increment1=0.0001;

increment1 = 0.01;

e1=[0:increment1:1];

s01=0;

% s1=[s01];

s1{1}=s01;

for i=2:length(e1)

% syms x

a = fsolve(@(x)increment1 - ((1/3)*k/(1+evide0)) * (x-s1{i-1})/x + ((1/3*G)*(x-s1{i-1})) ,(1+1i)*1000)

if isempty(a)

s1{i} = {0};

else

s1{i}=a;

end

if real(s1{i})>500

s1{i} = s1{1:(i-1)};

break

end

end

Equation solved.
fsolve completed because the vector of function values is near zero
as measured by the value of the function tolerance, and
the problem appears regular as measured by the gradient.

a = -1.2222e-05 - 1.8158e-19i

Equation solved.
fsolve completed because the vector of function values is near zero
as measured by the value of the function tolerance, and
the problem appears regular as measured by the gradient.

a = -2.5762e-05 + 1.2116e-14i

Equation solved.
fsolve completed because the vector of function values is near zero
as measured by the value of the function tolerance, and
the problem appears regular as measured by the gradient.

a = -3.9783e-05 + 3.8858e-14i

a = -5.4050e-05 + 2.9737e-14i

a = -6.8465e-05 + 2.2520e-14i

a = -8.2979e-05 + 2.6854e-14i

a = -9.7564e-05 + 2.3754e-14i

a = -1.1220e-04 + 2.5388e-14i

a = -1.2688e-04 + 2.6473e-14i

a = -1.4159e-04 + 2.7222e-14i

a = -1.5633e-04 + 2.7756e-14i

a = -1.7109e-04 + 2.7273e-14i

a = -1.8587e-04 + 2.7566e-14i

a = -2.0066e-04 + 2.7299e-14i

a = -2.1547e-04 + 2.7475e-14i

a = -2.3029e-04 + 2.7318e-14i

a = -2.4513e-04 + 2.7194e-14i

a = -2.5997e-04 + 2.7286e-14i

a = -2.7482e-04 + 2.7209e-14i

a = -2.8968e-04 + 2.7272e-14i

a = -3.0454e-04 + 2.7222e-14i

a = -3.1941e-04 + 2.7180e-14i

a = -3.3429e-04 + 2.7220e-14i

a = -3.4917e-04 + 2.7192e-14i

a = -3.6406e-04 + 2.7168e-14i

a = -3.7895e-04 + 2.7194e-14i

a = -3.9384e-04 + 2.7178e-14i

a = -4.0874e-04 + 2.7164e-14i

a = -4.2364e-04 + 2.7182e-14i

a = -4.3855e-04 + 2.7198e-14i

a = -4.5346e-04 + 2.7213e-14i

a = -4.6837e-04 + 2.7226e-14i

a = -4.8328e-04 + 2.7238e-14i

a = -4.9820e-04 + 2.7233e-14i

a = -5.1312e-04 + 2.7229e-14i

a = -5.2804e-04 + 2.7238e-14i

a = -5.4296e-04 + 2.7246e-14i

a = -5.5789e-04 + 2.7244e-14i

a = -5.7282e-04 + 2.7251e-14i

a = -5.8775e-04 + 2.7249e-14i

a = -6.0268e-04 + 2.7255e-14i

a = -6.1761e-04 + 2.7261e-14i

a = -6.3254e-04 + 2.7266e-14i

a = -6.4748e-04 + 2.7271e-14i

a = -6.6242e-04 + 2.7276e-14i

a = -6.7736e-04 + 2.7275e-14i

a = -6.9230e-04 + 2.7280e-14i

a = -7.0724e-04 + 2.7283e-14i

a = -7.2218e-04 + 2.7287e-14i

a = -7.3712e-04 + 2.7290e-14i

a = -7.5207e-04 + 2.7291e-14i

a = -7.6701e-04 + 2.7291e-14i

a = -7.8196e-04 + 2.7291e-14i

a = -7.9691e-04 + 2.7294e-14i

a = -8.1186e-04 + 2.7294e-14i

a = -8.2681e-04 + 2.7294e-14i

a = -8.4176e-04 + 2.7295e-14i

a = -8.5671e-04 + 2.7297e-14i

a = -8.7166e-04 + 2.7298e-14i

a = -8.8662e-04 + 2.7300e-14i

a = -9.0157e-04 + 2.7300e-14i

a = -9.1652e-04 + 2.7302e-14i

a = -9.3148e-04 + 2.7304e-14i

a = -9.4644e-04 + 2.7306e-14i

a = -9.6139e-04 + 2.7307e-14i

a = -9.7635e-04 + 2.7309e-14i

a = -9.9131e-04 + 2.7310e-14i

a = -0.0010 + 0.0000i

a = -0.0010 + 0.0000i

a = -0.0010 + 0.0000i

a = -0.0011 + 0.0000i

a = -0.0011 + 0.0000i

a = -0.0011 + 0.0000i

a = -0.0011 + 0.0000i

a = -0.0011 + 0.0000i

a = -0.0011 + 0.0000i

a = -0.0011 + 0.0000i

a = -0.0012 + 0.0000i

a = -0.0012 + 0.0000i

a = -0.0012 + 0.0000i

a = -0.0012 + 0.0000i

a = -0.0012 + 0.0000i

a = -0.0012 + 0.0000i

a = -0.0012 + 0.0000i

a = -0.0013 + 0.0000i

a = -0.0013 + 0.0000i

a = -0.0013 + 0.0000i

a = -0.0013 + 0.0000i

a = -0.0013 + 0.0000i

a = -0.0013 + 0.0000i

a = -0.0014 + 0.0000i

a = -0.0014 + 0.0000i

a = -0.0014 + 0.0000i

a = -0.0014 + 0.0000i

a = -0.0014 + 0.0000i

a = -0.0014 + 0.0000i

a = -0.0014 + 0.0000i

a = -0.0015 + 0.0000i

a = -0.0015 + 0.0000i

a = -0.0015 + 0.0000i

figure

plot(e1, real([s1{:}]))

grid

xlabel('e_1')

ylabel('s_1')

This runs without error. Make appropriate changes if it does not produce the desired result.

.

##### 2 Comments

rita richa
on 12 Feb 2022

thank you, I actually were searching for a positive real answer not an immaginary one but I found the problem, I had a mistake in the equation.

Thanks a lot for your time.

Star Strider
on 12 Feb 2022

My pleasure!

If my Answer helped you solve your problem, please Accept it!

.

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