Put multiple loglog plots on one figure
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Hello...I am trying to put 3 loglog plots on the same figure but this is not working. Any recommendations or small things I'm missing?
Thanks! :)
clear
clc
close all
format short
Re = 10^4:1000:10^8;
%Bruus
B = @(x) .25*(log((x/3.7)+(5.74./(Re).^.9)));
%Haaland
H = @(x) (1./(-1.8*log((x/3.7)^1.11+(6.9./Re)))).^2;
%Figure 1
eD1 = 0;
B1 = B(eD1);
H1 = H(eD1);
figure;
loglog(Re,B1,'r')
hold on
loglog(Re,H1,'--')
title('f vs. Re e/D = 0');
xlabel('Re');
ylabel('f');
legend('Bruus','Haaland');
grid on
回答（1 个）
madhan ravi
2018-10-31
0 个投票
Isn’t this normal? because the domain of the log function starts from 0+ to wards positive infinity that’s why it’s ignoring negative arguments.
5 个评论
madhan ravi
2018-10-31
There’s nothing wrong with the code because you have used hold on option which is supposed to hold multiple plots in one figure but as i said there’s some malfunctioning in mathematics.
madhan ravi
2018-10-31
See in your B , log(0/3.7) is exactly the same as log(0) log doesn’t contain zero as it’s domain since it starts from 0+ as mentioned before :)
madhan ravi
2018-10-31
编辑：madhan ravi
2018-10-31
See http://www.astro.umd.edu/~cychen/MATLAB/Logarithmic_Scaling_Info.html , read the last paragraph in the link.
Josh Glenn
2018-10-31
madhan ravi
2018-10-31
It should plot all the graphs if you fix the mathematical error.
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2018-10-31
2018-10-31
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