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

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 :)

Answer 1

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

[Tai-i]

THX very much !:)

Answer 2

[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.

[Tai-i]

thx very much :)