How to plot a matrix with loop of input Variables

I want to run the below code from the value of Bx 0 to 0.0118 with an interval of .00092 and plot it in e vs Bx, where e is a 4*1 matrix. I found some problem while plotting and I am very poor in working with loops.

Bx=0:.00092:0.0115;
B=0.5*1.978*0.467*30*Bx; 
D=-7.31;
E=-1.71;
Bz=0.5*1.969*0.467*30*0;
A=[2*D+3*Bz,sqrt(3)*B,sqrt(3)*E,0;sqrt(3)*B,Bz,2*B,sqrt(3)*E;sqrt(3)*E,2*B,-Bz,sqrt(3)*B;0,sqrt(3)*E,sqrt(3)*B,2*D-3*Bz]
e=eig(A)
D=eig(A,'matrix')
plot(Bx,e)

Here I wrote the code straight away and may not be correct,

Answer 1

[Walter Roberson]

syms Bx

B=0.5*1.978*0.467*30*Bx; 
D=-7.31;
E=-1.71;
Bz=0.5*1.969*0.467*30*0;
A=[2*D+3*Bz,sqrt(3)*B,sqrt(3)*E,0;sqrt(3)*B,Bz,2*B,sqrt(3)*E;sqrt(3)*E,2*B,-Bz,sqrt(3)*B;0,sqrt(3)*E,sqrt(3)*B,2*D-3*Bz]
e=eig(A)
fplot(e, [0, 0.0115])

[Muhammed Ajmal Pallithadathil Nazer]

Thank you, but it seems to take the Bx only the value of 0.0115 instead of the other values from 0 at a regular interval of .00092. Simply, it continuously plot the value of 0.0115 from 0 to 0.0115. Moreover, the answer from Joy Mondal works well.

• Item one
• Item two

Answer 2

[Joy Mondal]

Please try this code

[Muhammed Ajmal Pallithadathil Nazer]

Thank you Joy. Your code is working well. It would be great if you share how to change the scale of x and y axis in the graph as well as different colour for four different values of e as it quite difficult to identify from the graph

Answer 3

[Joy Mondal]

• clear all
• clc
• for Bx=0:.00092:0.0115
• i=0;
• B=0.5*1.978*0.467*30*Bx;
• D=-7.31;
• E=-1.71;
• Bz=0.5*1.969*0.467*30*0;
• A=[2*D+3*Bz,sqrt(3)*B,sqrt(3)*E,0;
• sqrt(3)*B,Bz,2*B,sqrt(3)*E;
• sqrt(3)*E,2*B,-Bz,sqrt(3)*B;
• 0,sqrt(3)*E,sqrt(3)*B,2*D-3*Bz];
• e=eig(A);
• j=0;
• for i=1:4
• j=j+1;
• ei=e(i,1);
• plot(Bx,ei,'ok')
• hold on
• end
• end

[Stephen23]

@Joy Mondal: please format your code correctly. It is very simple: first select the code text, then click the {} Code button above the textbox.

https://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

[Joy Mondal]

Thanks Stephen.

Answer 4

[Joy Mondal]

clc 
clear all 
for Bx=0:.00092:0.0115
  i=0;
  B=0.5*1.978*0.467*30*Bx;
  D=-7.31;
  E=-1.71;
  Bz=0.5*1.969*0.467*30*0;
  A=[2*D+3*Bz,sqrt(3)*B,sqrt(3)*E,0;
      sqrt(3)*B,Bz,2*B,sqrt(3)*E;
      sqrt(3)*E,2*B,-Bz,sqrt(3)*B;
      0,sqrt(3)*E,sqrt(3)*B,2*D-3*Bz];
      e=eig(A);
      j=0;
      for i=1:4
          j=j+1;
          ei=e(i,1);
          if j==1
              plot(Bx,ei,'dk')
          elseif j==2
              plot(Bx,ei,'og')
            elseif j==3
              plot(Bx,ei,'sb')
                elseif j==4
              plot(Bx,ei,'xm')
          end
          hold on
      end
end

end