Error in the for loop or equality sign

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Faisal Baig
Faisal Baig on 21 May 2019
Answered: Jos (10584) on 21 May 2019
Hello,
I am using following code to check the discharges in the pipelines connecting three reservoirs. But the Loop is not working I guess. Could anybody tell the error?
Ela=100;
Elb=70;
Elc=30;
ka=1563.085;
kb=38.10;
kc=12729.55;
x=70:0.01:75;
for i=1:x;
Qa=sqrt((Ela-x)/ka);
Qb=sqrt((x-Elb)/kb);
Qc=sqrt((x-Elc)/kc);
if Qb+Qc==Qa
disp(Qa)
disp(Qb)
disp(Qc)
break
else
continue
end
end
  5 Comments
Walter Roberson
Walter Roberson on 21 May 2019
Please answer my question about the expected values of i
Faisal Baig
Faisal Baig on 21 May 2019
I can use
'for x= 70:0.01:75'
instead of
x= 70:0.01:75;
for i = 1:x;
So basically, I just want to give range of my values to find Qa, Qb and Qc. i doesn't matter

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Answers (1)

Jos (10584)
Jos (10584) on 21 May 2019
Welcome to the world of floating point arithmetic, where
if 0.1+0.2 == 0.3
disp('0.1+0.2 equals 0.3')
else
disp('0.1+0.2 does not equal 0.3')
end
More info here:
You want to check with a tolerance:
if abs(Qa+Qb-Qc) < 1e-10
disp('Qa+Qb practically equals Qc')
end

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