displaying values in command window
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hi, trying to display some values but am not sure how to go about it, this is a pH array, Vb is volume of base added. What i am trying to do is display the midpoint to equivalence which is the half of Vb_ev and then display the corresponding pH value at midpoint, which i know is approx 4.756. see on from line 6 from the bottom.
format short
Kw = 1e-14;
Ka = 1.755388e-5;
pKa = 4.756;
%
Ca = 0.5;
Cb = 0.1;
Va = 100;
Vb = 0.05:0.05:2000;
Ma = (Ca * Va) / 1000;
Mb = (Cb .* Vb) ./ 1000;
for i = 1:length(Mb)
M_excess = Ma - Mb(i);
if abs(M_excess)<eps
Hplus = Ka * ((Ma_final * 0.999999) ./ Mb_final);
Vb_ev = Vb(i);
pH_ev = pH(end);
elseif M_excess > 0
Ma_final = (M_excess * 1000) ./ (Va + Vb(i));
Mb_final = (Mb(i) * 1000) ./ (Va + Vb(i));
Hplus = Ka * (Ma_final ./ Mb_final);
elseif M_excess < 0
OH = (M_excess * 1000 * (-1)) ./ (Va + Vb(i));
Hplus = Kw ./ OH;
end
pH(i) = -log10(Hplus);
end
%
Vb_Mid_Pt1 = (Vb_ev)*0.5;
pH_Mid_Pt1 = i want to display pH at Vb_Mid_Pt1;
disp('The Volume is, mL:')
disp(Vb_Mid_Pt1)
disp('The pH is:')
disp(pH_Mid_Pt1)
2 个评论
Jan
2013-8-6
"No luck" is a not a good description of the problem and of what you actually want. The less the readers have to guess, the more likely is a matching answer.
采纳的回答
kedija
2013-8-6
the reason you are getting such error is the index Vb_Mid_Pt1 is not integer. if u cast that it works fine. here you go
format short
Kw = 1e-14;
Ka = 1.755388e-5;
pKa = 4.756;
%
Ca = 0.5;
Cb = 0.1;
Va = 100;
Vb = 0.05:0.05:2000;
Ma = (Ca * Va) / 1000;
Mb = (Cb .* Vb) ./ 1000;
for i = 1:length(Mb)
M_excess = Ma - Mb(i);
if abs(M_excess)<eps
Hplus = Ka * ((Ma_final * 0.999999) ./ Mb_final);
Vb_ev = Vb(i);
pH_ev = pH(end);
elseif M_excess > 0
Ma_final = (M_excess * 1000) ./ (Va + Vb(i));
Mb_final = (Mb(i) * 1000) ./ (Va + Vb(i));
Hplus = Ka * (Ma_final ./ Mb_final);
elseif M_excess < 0
OH = (M_excess * 1000 * (-1)) ./ (Va + Vb(i));
Hplus = Kw ./ OH;
end
pH(i) = -log10(Hplus);
end
%
Vb_Mid_Pt1 = uint16(Vb_ev)*0.5;
pH_Mid_Pt1 = pH(Vb_Mid_Pt1);%i want to display pH at Vb_Mid_Pt1;
disp('The Volume is, mL:')
disp(Vb_Mid_Pt1)
disp('The pH is:')
disp(pH_Mid_Pt1)
4 个评论
更多回答(1 个)
David Sanchez
2013-8-6
I hope this is what you want to do:
my_var = 3;
fprintf('The value of my variable is : %g \n' ,my_var);
OUTPUT:
The value of my variable is : 3
0 个评论
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