## HELP! I need to plot my values from if statement, and cant figure out how

Asked by ragheed idrees

### ragheed idrees (view profile)

on 7 Jun 2019
Latest activity Commented on by Raghunandan V

### Raghunandan V (view profile)

on 10 Jun 2019
if H < 1.5 %Pressure drop is less than 1.5 psi
D = (Qc.^0.381)/(19.17*(H./(Cr.*L))^0.206);
elseif H >= 1.5 %Pressure drop is greater than or equal to 1.5 psi
D = (Qc.^0.381)/(18.93*((P1a.^2-P2a.^2).*Y./Cr.*L)^0.206);
end
xx = linspace(0,2*Qc,1000);
fplot
this is the part of the function that does the calculation and I can't figure out how to plot the D vs. xx

Rik

### Rik (view profile)

on 7 Jun 2019
I you want to add a marker at only a single point, it is easier to use hold on and a single point with the appropriate marker at the appropriate position.
ragheed idrees

### ragheed idrees (view profile)

on 7 Jun 2019
I see, my dilemma is that for me to plot it i need a for loop, but to get the correct asnwer (point on plot) I only get it without the for loop, how do I plot the graph and at the same time find the value without the for loop?
Rik

### Rik (view profile)

on 8 Jun 2019
Which of the 1000 point do you want to put a marker?

### Release

R2019a

Answer by Raghunandan V

### Raghunandan V (view profile)

on 7 Jun 2019

Hi,
Just a small correction in the code
if H < 1.5 %Pressure drop is less than 1.5 psi
D = (Qc.^0.381)/(19.17*(H./(Cr.*L))^0.206);
else %Pressure drop is greater than or equal to 1.5 psi
D = (Qc.^0.381)/(18.93*((P1a.^2-P2a.^2).*Y./Cr.*L)^0.206);
end
xx = linspace(0,2*Qc,1000);
plot(xx, D)
This is only possible if your xx and D are of same dimention

ragheed idrees

### ragheed idrees (view profile)

on 7 Jun 2019
thank you sir, I have done that but now i cant find the value for D in order to point it on the plot. Can you please help me with that?
Raghunandan V

### Raghunandan V (view profile)

on 10 Jun 2019
Oh! Are all the inputs to calculate the value of D available?