Index exceeds the number of array elements

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0 个投票

Hello All, I'm encountring the following error when I run my code: Index exceeds the number of array elements. My code is simple and shown below:

format longg
syms p1 
nm = 3e15;
s01=1;
v1=4.82e20;
tao00=1e-13;
p00=3;
q00=21;
q11=10.6;
R=1.9872036e-3;
T=295;
V1=16.7;
K1=3.27e19;
   t1=linspace(1,1e6,10);
taop1=3.6;
S1=4.7;
A1=4.74e3;
Nm = A1*nm;
W1=(Nm/(K1*V1));
y1=q00;
a1= ((s01*tao00*v1)/(nm))*exp((y1)/(R*T));
Z1=(1/(1+a1*p00));
Y1 = (p00/(1+(a1*p00)));
eq1 = ((t1./taop1)==(log(p00./p1))+((a1.*W1).*(Z1-(1./(1+a1.*p1))+log(((1+a1.*p1)./p1).*Y1))));
 for i=t1
    pp1=0;
 pp1(i) = vpa(vpasolve(eq1(i),p1),11);
end
Index exceeds the number of array elements. Index must not exceed 10.

Error in indexing (line 1079)
            R_tilde = builtin('subsref',L_tilde,Idx);
pp1;
% loglog(t1,pp1,'o')
% ylim([1e-11 1e-2])
% xlim([10 1e6])

Thank you all for the help in advance.

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N/A 2023-1-12

When I replace the lincpace with the regular t1=1:1:10e6; i get the following error:

Unable to perform assignment because the left and right sides have a different number of elements.

Error in sym/privsubsasgn (line 1128)

L_tilde2 = builtin('subsasgn',L_tilde,struct('type','()','subs',{varargin}),R_tilde);

Error in sym/subsasgn (line 965)

C = privsubsasgn(L,R,inds{:});

Error in Langmuir_Q21 (line 44)

pp1(i) = vpa(vpasolve(eq1(i),p1),6);

Walter Roberson 2023-1-12

Assign the results of the vpasolve to a variable. Test to see if the variable is empty or has more one value.

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Answer 1

Walter Roberson 2023-1-12

在 MATLAB Online 中打开

1 个投票

A number of the solutions involve complex values.

If you start t1 at 1 then the first few output values are enough greater that the rest are not visible on the graph.

When you start t1 at 1 then you get negative components for the real value of some of the results, so you cannot plot on the log scale. There are negative components for most of the imaginary parts so you cannot use log scale for that either.

format longg

syms p1

Q = @(v) sym(v);

nm = Q(3)*Q(10)^15;

s01 = Q(1);

v1 = Q(482)*Q(10)^18;

tao00 = Q(1)*Q(10)^(-13);

p00 = Q(3);

q00 = Q(21);

q11 = Q(106)/Q(10);

R = Q(19872036)*Q(10)^(-10);

T = Q(295);

V1 = Q(167)/Q(10);

K1 = Q(327)*Q(10)^17;

taop1 = Q(36)/Q(10);

S1 = Q(47)/Q(10);

A1 = Q(4740);

Nm = A1*nm;

W1=(Nm/(K1*V1));

y1=q00;

a1= ((s01*tao00*v1)/(nm))*exp((y1)/(R*T));

Z1=(1/(1+a1*p00));

Y1 = (p00/(1+(a1*p00)));

t1 = linspace(1,50,50);

t2 = linspace(50,200,50);

t3 = linspace(200,1e6,500);

syms T1

eq1 = ((T1./taop1)==(log(p00./p1))+((a1.*W1).*(Z1-(1./(1+a1.*p1))+log(((1+a1.*p1)./p1).*Y1))));

pp1 = arrayfun(@(E)vpasolve(E,p1, 1e-5), subs(eq1, T1, t1));

pp2 = arrayfun(@(E)vpasolve(E, p1, 1e-5), subs(eq1, T1, t2));

pp3 = arrayfun(@(E)vpasolve(E, p1, 1e-5), subs(eq1, T1, t3));

subplot(2,3,1);

plot(t1, real(pp1));

title('p1 real');

subplot(2,3,2);

plot(t2, real(pp2));

title('p2 real');

subplot(2,3,3);

plot(t3, real(pp3));

title('p3 real');

subplot(2,3,4);

plot(t1, imag(pp1))

title('p1 imag')

subplot(2,3,5);

plot(t2, imag(pp2))

title('p2 imag');

subplot(2,3,6);

plot(t3, imag(pp3))

title('p3 imag');

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N/A 2023-1-13

Thank you so much! I understand now whats going on here! I really apprecitae your help.

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Answer 2

Torsten 2023-1-12

编辑：Torsten 2023-1-12

在 MATLAB Online 中打开

1 个投票

I suggest you insert values for p1 and solve for t1. This will be easier than the other way round.

format longg
syms p1 t1
nm = 3e15;
s01=1;
v1=4.82e20;
tao00=1e-13;
p00=3;
q00=21;
q11=10.6;
R=1.9872036e-3;
T=295;
V1=16.7;
K1=3.27e19;
T1=linspace(1,10,10);
taop1=3.6;
S1=4.7;
A1=4.74e3;
Nm = A1*nm;
W1=(Nm/(K1*V1));
y1=q00;
a1= ((s01*tao00*v1)/(nm))*exp((y1)/(R*T));
Z1=(1/(1+a1*p00));
Y1 = (p00/(1+(a1*p00)));
eq1 = ((t1./taop1)==(log(p00./p1))+((a1.*W1).*(Z1-(1./(1+a1.*p1))+log(((1+a1.*p1)./p1).*Y1))));
for i=1:numel(T1)
    pp1(i) = double(vpasolve(subs(eq1,t1,T1(i)),p1,11));
end
pp1.'
ans = 10×1
          2.27239538495313
          1.72126026208779
          1.30379462550031
         0.987578963504762
         0.748056626521194
         0.566626808824952
         0.429200048722703
         0.325104070308059
         0.246254996746847
         0.186529573242241

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Torsten 2023-1-13

编辑：Torsten 2023-1-13

在 MATLAB Online 中打开

I didn't use

pp1(i) = vpa(solve(eq1(i),p1,'IgnoreAnalyticConstraints',1),6);

anywhere in the code I provided.

And the decrease towards 0 has nearly ended at t=10. There is no need to solve up to 1e6.

But if you want: T1 = linspace(1,1e6,100) will also work:

format longg

syms p1 t1

nm = 3e15;

s01=1;

v1=4.82e20;

tao00=1e-13;

p00=3;

q00=21;

q11=10.6;

R=1.9872036e-3;

T=295;

V1=16.7;

K1=3.27e19;

T1=linspace(1,1e6,100);

taop1=3.6;

S1=4.7;

A1=4.74e3;

Nm = A1*nm;

W1=(Nm/(K1*V1));

y1=q00;

a1= ((s01*tao00*v1)/(nm))*exp((y1)/(R*T));

Z1=(1/(1+a1*p00));

Y1 = (p00/(1+(a1*p00)));

eq1 = ((t1./taop1)==(log(p00./p1))+((a1.*W1).*(Z1-(1./(1+a1.*p1))+log(((1+a1.*p1)./p1).*Y1))));

for i=1:numel(T1)

pp1_help = double(vpasolve(subs(eq1,t1,T1(i)),p1,11));

pp1_help = pp1_help(real(pp1_help)>0 & abs(imag(pp1_help))<1e-8);

if ~isempty(pp1_help)

pp1(i) = real(pp1_help(1));

else

pp1(i) = 0.0;

end

plot(T1,pp1)

N/A 2023-1-13

Thank you very much! This is extremely helful. I appreicte your time and efforts.

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