Problem with 2 plots, one in not showing and second one is showing up empty.

hello,

so I have 2 small codes, with 2 plots, the first one is showing the plot empty and the second one is not showing at all, can anyone help me please,

thanks,

first code:

Ppvmax= 800; % watt/m^2
Tdl= 12; %daytime duration
Tsr=7; % sunrise time
Ttod daytime at time of day
for Ttod=[0:1:24];
    Ppv = Ppvmax * sin( pi*(Ttod-Tsr)/Tdl );
    plot(Ttod,Ppv)
    hold on;
end

second code:

Pfdg=50;
Pfz= 22; PLi=267; Psh= 313; Pac=403; Ptv=86; Pwm=1.2; Pmicro=0.33; Pnot= 13; Pwater=8.5;
for t=[0:1:24]
    if 5<t<8 
        a=0
    else a=1;
    end
    if 17<t<21
        b=0 
    else b=1 
        Pdem = symsum(Pfdg,0,24) + Pfz + PLi + a*Psh + b*Psh + a*Pac + b*Pac + a*Ptv + b*Ptv + a*Pnot + b*Pnot + a*b*Pwater +a*b*Pwm + Pmicro
        plot(t,Pdem)
        hold on;
    end
end

[dpb]

Ppvmax= 800; % watt/m^2
Tdl= 12; %daytime duration
Tsr=7; % sunrise time
Ttod=[0:1:24];
Ppv = Ppvmax * sin( pi*(Ttod-Tsr)/Tdl );
plot(Ttod,Ppv)
hold on;
Pfdg=50;
Pfz= 22; PLi=267; Psh= 313; Pac=403; Ptv=86; Pwm=1.2; Pmicro=0.33; Pnot= 13; Pwater=8.5;
t=Ttod;                             % just to save redefining variable t below
a=zeros(size(t)); a(t>=8)=1;        % define constant by TOD
b=ones(size(t)); b(t>17 & t<21)=0;
Pdem=Pfdg+Pfz+PLi+(a+b)*(Psh+Pac+Ptv+Pnot)+a.*b*(Pwater+Pwm) + Pmicro;
plot(t,Pdemsum

[jana nassereddine]

thanks a lot

Answer 1

[Allen]

Jana,

For both examples you are only plotting a single set of scalar values (e.g. a point) during each interation of the for loop. If that is your intention, then you will need to define a point marker style in your plot function.

plot(Ttod,Ppv,'-*')

However, to plot lines using the plot function you need to provide numerical arrays as the inputs to the plot function.

% Your initial fixed scalar values
Ppvmax = 800; % watt/m^2
Tdl = 12; %daytime duration
Tsr = 7; % sunrise time

% Setup Ttod as a vector array with values.
% The default step size when creating vectors using a semicolon is 1.
Ttod = 0:24; % Same as: Ttod = 0:1:24;

% Solve Ppv for each value in the Ttod array
Ppv = Ppvmax*sin(pi*(Ttod-Tsr)/Tdl); % size(Ppv) is equal to size(Ttod)
% An equivalent, but less efficient method to solve for each value can be
% done using a for-loop. However, this might make more sense as to what is
% being created.
for i=1:length(Ttod) % The for-loop index should start at 1, since array indices are positive scalar values.
    Ppv(i) = Ppvmax*sin(pi*(Ttod(i)-Tsr)/Tdl);
end

% Plot Ttod and Ppv on the x- and y-axes, respectively.
plot(Ttod,Ppv)

The syntax you are using to represent a range of values in your second plot is not supported. You can represent them using the following.

% 5<t<8
t>5 & t<8
% 17<t<21
t>17 & t<21
% For OR statements use, |
% Depending on the use you made need double operators (&&, ||, etc.)
t>5 && t<8
t>17 && t<21

I do not have the symbolic toolbox and am unfamiliar with the symsum function, but it also does not appear correctly setup. Below is a link to the help file for the symsum function.

https://www.mathworks.com/help/symbolic/sym.symsum.html

Here is my attempt to setup the remainder of the code correctly, but may need some adjustments to get symsum to work properly.

% Initialize scalar inputs
Pfdg = 50;
Pfz = 22;
PLi = 267;
Psh = 313;
Pac = 403;
Ptv = 86;
Pwm = 1.2;
Pmicro = 0.33;
Pnot = 13;
Pwater = 8.5;

% Initialize array input variables
t = 0:24;
a = ones(size(t));
b = a;
a(t>5 & t<8) = 0;
b(t>17 & t<21) = 0;

% Calculate Pdem array and plot results. Note that dot-notation (.* vs *) is required
% to multiple arrays element-wise and they must also be of equal size.
Pdem = symsum(Pfdg,0,24) + Pfz + PLi + a*Psh + b*Psh + a*Pac + b*Pac + a*Ptv + b*Ptv + a*Pnot + b*Pnot + a.*b*Pwater +a.*b*Pwm + Pmicro
plot(t,Pdem)

Answer 2

[Cris LaPierre]

You need to include a markerstyle in your plot commands since you are plotting your data one point at a time. When you plot a single point without a marker, it is not visible.

The other option is to use your for loop to create a vector, and then plot the vector.

In your second case, you should specifly your if statements and two conditions. You will then have the same issue with plotting a single point at a time.

t=0;
% Always true
5<t<8 

ans = logical
   1

% specifying as two conditions
t>5 && t<8

ans = logical
   0