How to generate a loop for vpasolve function

I intend to solve a non-transcendental equation using 'vpasolve' for several values of initial guesses.

I do not know how to create a decent loop for this. I tried following code but it does not work:

syms x

y = 1 + cos(x) * cosh(x)

xinitial = linspace(0,30,61);

n = length(xinitial);

for i = 1 : n

R = vpasolve(y == 0, x, xinitial(i))

%R(i,1) = xinitial(i) * 1

end

using R gives values in seperate, and using R(i,1), Matlab does not work.

Do you know how to put the obtained results from vpasolve into a row/columbn matrix?

another interesting point is, it works with 'fzero' function:

f = @(x)1+cos(x)*cosh(x)

xi = linspace(0,10,11)

for i = 1 : length(xi)

A(i,1) = fzero(f,xi(i))

end

I don't know why it does not work with vpasolve function (I mean the looping step)

Thanks a lot

[Peter O]

Alireza,

As you've noted, R gets overwritten on each pass of the loop. Unfortunately I don't have the symbolic math toolbox so I can't test your code exactly, but the indexing should work since x is a scalar. In the code you posted, you're assigning the initial guess to R instead of the solved value. Perhaps this is the issue?

Try this. I've preallocated R prior to the loop (a bit more efficient). It should give you a column vector of symbolic variables matching the (row) vector of xinitial.

syms x 
y = 1 + cos(x) * cosh(x)
xinitial = linspace(0,30,61);
n = length(xinitial);
R = sym('0',[n,2]) 
for i = 1 : n
    R(i,1) = vpasolve(y == 0, x, xinitial(i))
end 

Answer 1

[Walter Roberson]

    R(i, 2) = vpasolve(y == 0, x, xinitial(i));
    R(i,1) = xinitial(i);

Or you could

R = arrayfun(@(xi) vpasolve(y==0,x,xi), xinitial) ;