Logarithmic scale problem in 2D graph

Question

Yordani 2022-12-27

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链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1885142-logarithmic-scale-problem-in-2d-graph

评论： Star Strider 2022-12-28

Hello! I am trying to program equation (2) and make graph number 1, specifically the curve that Masetti [21] says, but when I do it I have an error where the graph starts, could someone please help me :(

Graph 1

Mine :(

My code:

u1=68.5;

umax=1414;

u2=56.1;

Cr=9.2e16;

Cs=3.41e20;

alfa=0.711;

beta=1.98;

N1=1e16;

N2=1e16;

N3=1e21;

index=0;

k = N1:N2:N3;

for Ne = 1:length(k)

index = index + 1 ;

u(index) = u1 + ((umax-u1)/(1+(k(Ne)/Cr)^alfa)) - ((u2)/(1+(Cs/k(Ne))^beta));

f(index) = k(Ne);

x(index) = f(index) ;

y(index) = u(index);

end

semilogx(x,y)

yticklabels({'0','100','200','300','400','500'})

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Karim 2022-12-27

编辑：Karim 2022-12-27

在 MATLAB Online 中打开

When I try it (see below) I obtain the same curve as you have. The values and the equation are the same as from the snapshot of the paper. Hence, I would say that your curve, also at the start, is indeed correct.

If you want to obtain the same curve as 'graph1' you will need another set of parameters. Are you certain that those parameters corespond to that graph?

EDIT: disabled the ytick label text, as this could lead to wrong interpretation of the data

mu1 = 68.5;

mumax = 1414;

mu2 = 56.1;

Cr = 9.2e16;

Cs = 3.41e20;

alfa = 0.711;

beta = 1.98;

Ne = logspace(16,21,1000);

mu = mu1 + ( (mumax-mu1) ./ (1+(Ne./Cr).^alfa) ) - ( mu2 ./ (1+(Cs./Ne).^beta) );

figure

semilogx(Ne,mu)

%yticklabels({'0','100','200','300','400','500'})

grid on

xlabel('$N_{e}$','interpreter','latex','FontSize',20)

ylabel('$\mu$','interpreter','latex','FontSize',20)

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Answer 1

Star Strider 2022-12-27

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1885142-logarithmic-scale-problem-in-2d-graph#answer_1137002

在 MATLAB Online 中打开

I don’t see anything wrong with the code (however I rewrote the μ assignment to make it a bit easier for me to understand in the context of the equation provided).

I suspect there’s something wrong with the y-axis scaling (as expressed in the yticklabels call), however not knowing what that scaling multiplication is, I can’t determine if there’s a problem.

Plotting it without the scaling —

u1=68.5;

umax=1414;

u2=56.1;

Cr=9.2e16;

Cs=3.41e20;

alfa=0.711;

beta=1.98;

N1=1e16;

N2=1e16;

N3=1e21;

Ne = N1:N2:N3;

for k = 1:length(Ne)

u(k) = u1 + ((umax-u1)/(1+(Ne(k)/Cr)^alfa)) - (u2/(1+(Cs/Ne(k))^beta));

end

semilogx(Ne,u)

xlabel('Ne')

ylabel('\mu')

% yticklabels({'0','100','200','300','400','500'})

.

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Yordani 2022-12-28

I already found the mistake! Thanks for your contribution!

Star Strider 2022-12-28

My pleasure!

Just out of curiosity, what was the mistake? We’d all like to know!

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