MATLAB: Is there anyway I can reduce this program to a few lines

cosine functionreduction

Hello,

I would like to reduce this program to 3 lines only or more but not explicit, Any ideas?

      x1=-3*pi:0.1:-2*pi;
      y1=-cos(x1);
      x2=-2*pi:0.1:-pi;
      y2=cos(x2);
      x3=-pi:0.1:0;
      y3=-cos(x3);
      x4=0:0.1:pi;
      y4=cos(x4);
      x5=pi:0.1:2*pi;
      y5=-cos(x5);
      x6=2*pi:0.1:3*pi;
      y6=cos(x6);
      plot(x1,y1,x2,y2,x3,y3,x4,y4,x5,y5,x6,y6)

Best Answer

   x={-3*pi:0.1:-2*pi,
       -2*pi:0.1:-pi,
       -pi:0.1:0,
       0:0.1:pi,
        pi:0.1:2*pi,
        2*pi:0.1:3*pi}.';
    p=[x;cellfun(@(c,n)(-1)^n*cos(c),x,num2cell(1:6),'uni',0)];
    plot(p{:})

Related Solutions

MATLAB: Help with for loop calling values of variables from an array.

size of x, y were not same in your code. Tp plot vectors x, y must have same dimensions.

b={.25, .25, .5}; d={.25, .75, .5};
for n=1:1:3;    
    p=cell2mat(b(n));    
    z=cell2mat(d(n));    
    Ca = 4*pi^2/((pi^2-8)*(p^2-z*z)-2*pi*(pi-2)*p+pi^2);    
    x1 = 0:0.01:(p/2); y1 = Ca*sin(pi*x1/p);    
    x2 = p/2:0.01:(1-z)/2; y2 = ones(size(x2))*Ca;    
    x3 = (1-z)/2:0.01:(1+z)/2; y3 = Ca*cos(pi*(x3-(1-z)/2)/z);
    x4 = (1+z)/2 :0.01:1-p/2; y4 = -ones(size(x4))*Ca;
    x5 = (1-p/2):0.01:1; y5 = Ca*sin(pi*(x5-1)/p);
      x = [x1 x2 x3 x4 x5]; y = [y1 y2 y3 y4 y5]; 
      plot(x,y); 
      hold on;
  end

MATLAB: FSOLVE requires all values returned by functions to be of data type double.

If you want to solve a system of equations symbolically or using symbolic variables, use the solve function instead of fsolve. The fsolve function requires that the output of the function you specify as the first input be double precision numbers, not symbolic expressions.

If you must use fsolve with symbolic variables inside the function, you must convert those symbolic expressions into numbers using double before returning the numbers (not the symbolic expressions) from the function.

As a very simple example, put all this code into a function example373677.m and run it:

function y = example373677
y = fsolve(@mysubfun, 3);
 
function z = mysubfun(q)
x = sym('x');
r = x.^3-2*x-5;
z = double(subs(r, q));

Of course, with solve this is easier.

syms x
y = solve(x.^3-2*x-5)

You may need to use vpa to approximate y numerically.

vpa(y)

One of the solutions returned in y should match the result you received from running the function.

Best Answer

Related Solutions

MATLAB: Help with for loop calling values of variables from an array.

MATLAB: FSOLVE requires all values returned by functions to be of data type double.

Related Question