How to convert each equation calculations into FOR Loop form

This is the code for each calculations (Normal form)

p = linspace(1,5);

AdK2 = 1.4;

Eff_Ratio_17 = 1-(p.^AdK2-1)./(AdK2*(p-1)*(17^(AdK2-1)))

Eff_Ratio_19 = 1-(p.^AdK2-1)./(AdK2*(p-1)*(19^(AdK2-1)))

Eff_Ratio_21 = 1-(p.^AdK2-1)./(AdK2*(p-1)*(21^(AdK2-1)))

Eff_Ratio_23 = 1-(p.^AdK2-1)./(AdK2*(p-1)*(23^(AdK2-1)))

Eff_Ratio_25 = 1-(p.^AdK2-1)./(AdK2*(p-1)*(25^(AdK2-1)))

plot(p,Eff_Ratio_17,p,Eff_Ratio_19,p,Eff_Ratio_21,p,Eff_Ratio_23,p,Eff_Ratio_25)

ylabel('Thermal Efficiency');

xlabel('Injection Ratio');

Figure 1

I tried to convert into a for loop form to simplify the structure but I keep getting wrong graph and the equation calculations seems off

p = linspace(1,5);

AdK2 = 1.4;

for R = 17:2:25

Eff_Ratio = 1-((p.^(AdK2-1))./(AdK2*(R^(AdK2-1)*(p-1))));

plot(p,Eff_Ratio)

end

ylabel('Thermal Efficiency');

xlabel('Injection Ratio');

Figure 2

Can someone point out what's wrong with my code arrangment ?

The graph that I want to get is Figure 1.**

Answer 1

[David Hill]

No loop needed.

p = linspace(1.001,5);
AdK2 = 1.4;
Eff_Ratio = 1-(p.^AdK2-1)./(AdK2*(p-1))./((17:2:25).^(AdK2-1))';
plot(p,Eff_Ratio)
ylabel('Thermal Efficiency');
xlabel('Injection Ratio');

[Yeong Haoyee]

Thanks a lot ! I follow your advice and it works! I realized my mistake when trying to do the code the equation.

p = linspace(1.001,5);

AdK2 = 1.4;

Eff_Ratio = 1-(p.^AdK2-1)./(AdK2*(p-1))./((17:2:25).^(AdK2-1))';

plot(p,Eff_Ratio)

ylabel('Thermal Efficiency');

xlabel('Injection Ratio');

Instead of using the semilogx, I change it to plot to get the figure 1 picture(Just editted the questions to show the graph I'm trying to get)

But I have a question. Why do you use 1.001 instead of just 1 ?

[David Hill]

First point would by nan (dividing by zero... p-1)

Answer 2

[Davide Masiello]

You need a 'hold on' in order to keep previous lines in the plot at each iteration.

But you can do even better in this way

p = linspace(1,5);
AdK2 = 1.4;
R = 17:2:25;
Eff_Ratio = zeros(length(R),length(p));
for idx = 1 : length(R)
    Eff_Ratio(idx,:) = 1-((p.^(AdK2-1))./(AdK2*(R(idx)^(AdK2-1)*(p-1))));
end
figure
semilogx(p,Eff_Ratio)
ylabel('Thermal Efficiency');
xlabel('Injection Ratio');

Answer 3

[Voss]

Eff_Ratio_17 = 1-(p.^AdK2-1)./(AdK2*(p-1)*(17^(AdK2-1)))
Eff_Ratio_19 = 1-(p.^AdK2-1)./(AdK2*(p-1)*(19^(AdK2-1)))
Eff_Ratio_21 = 1-(p.^AdK2-1)./(AdK2*(p-1)*(21^(AdK2-1)))
Eff_Ratio_23 = 1-(p.^AdK2-1)./(AdK2*(p-1)*(23^(AdK2-1)))
Eff_Ratio_25 = 1-(p.^AdK2-1)./(AdK2*(p-1)*(25^(AdK2-1)))

becomes:

for R = 17:2:25
    Eff_Ratio = 1-(p.^AdK2-1)./(AdK2*(p-1)*(R^(AdK2-1)))
end

(the only change is the substitution of R in place of {17, 19, ...})

In making this change, you have introduced another set of parentheses, which changes the expression:

Eff_Ratio = 1-((p.^(AdK2-1))./(AdK2*(R^(AdK2-1)*(p-1))));

Notice: p.^(AdK2-1) vs p.^AdK2-1