When running code it returns >> pp01 Error using plot Error in color/linetype argument. Error in pp01 (line 33) plot(t(:),​z(:,1),'W'​,t(:),z(:,​2),'F')

function pp01

clear

global As Qt g A c

As=15;

Qt=10;

g=9.81;

A=(121/64)*pi;

c=0.02;

z1_initial=10;

z2_initial=25;

N=1000;

h=0.5;

t=zeros(N,1);

z=zeros(N,2);

t(1)=0;

z(1,1)=z1_initial;

z(1,2)=z2_initial;

for n=1:N-1

t(n+1)=t(n)+h;

z(n+1,:)=z(n,:)+h*f(t(n),z(n,:));

z(n+1,:)=z(n,:)+0.5*h*(f(t(n),z(n,:))+f(t(n+1),z(n+1,:)));

end

%plot(t(:),z(:,1),'W',t(:),z(:,2),'F')

Figure 2

Plot(z(:,1),z(:,2))

[t,z];

return

function dzdt=f(~,z)

global As Qt g A c

%dzdt(1)=z(2);

%dzdt(2)=-z(1);

dzdt(1)=(1/As)*(z(2)-Qt);

dzdt(2)=-g*(A/2)*(z(1)+(c*abs(z(2))*z(2)));

return

Answer 1

[Walter Roberson]

'W' is valid as a code for White but 'F' is not a color abbreviation and is not a marker shape code. Valid codes are

• b: blue
• c: cyan
• d: diamond marker
• g: green
• h: hexagon marker
• k: black
• m: magenta
• o: circle marker
• p: pentagram marker
• r: red
• s: square marker
• v: down triangle marker
• w: white
• x: x marker
• y: yellow
• *: * marker
• +: + marker
• . : dot marker
• ^: upward triangle marker
• <: left triangle marker
• >: right triangle marker
• - and : are used for line styles

[Lucy Raistrick]

That seems to have fixed an issue but now this error is appearing

>> pp01

Undefined function or variable 'Figure'.

Error in pp01 (line 35)

Figure 2

[Walter Roberson]

MATLAB has been case sensitive for quite a while now. The graphics routines all start with lower case letters. figure and plot not Figure and Plot