why " if " condition of expression is tenable , but it cant do the statement ?

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Tai-i
Tai-i 2012-5-2
here is my code
syms E Eg V g;
c=3 .*(10.^8); % m/s
h=4.1361e-015; % eV.s
k=8.62E-5;
Tc=300;
Eg=1.48;
Ei=0.5;
Ec=Eg-Ei;
a=quad( @(E)(E.^2) ./ (exp(E./0.5172)-1), Ei , Ec)- quad(@(E)(E.^2) ./ (exp(( E-Uiv )./0.0259)-1),Ei,Ec);
b=quad( @(E)(E.^2) ./ (exp(E./0.5172)-1), Ec , Eg)-quad(@(E)(E.^2) ./ (exp(( E-Uci )./0.0259)-1),Ec,Eg);
for Uiv = 0.484:0.0001:0.485
for Uci = 0.905:0.0001:0.906
a
b
if a==b
Uiv
Uci
end
end
end
i check a and b but it doesnt give me Uiv & Uci
thx :)

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采纳的回答

Walter Roberson
Walter Roberson 2012-5-2

更多回答（1 个）

Venn Ravichandran
Use:
if abs(a-b) <= eps
% my operations here
end
Floating point comparisons can cause such errors, since you will have small changes (~1e-10) in the numbers generated by your {for} loop.

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