remove brace indexing from 1x1 matrix

I have a list of equations written with a fprintf loop and imported with importdata:

6×1 cell array

{'-0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(1.5707963268)+sin(x(2))*sin(1.5707963268)) ' }

{'-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634)) '}

{'-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634)) ' }

{'-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634)) ' }

{'-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634)) '}

{'-0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(0.0000000000)+sin(x(2))*sin(0.0000000000)) ' }

using

A=importdata('equations list.txt');

B=transpose(A);

C=cell2mat(B);

I get the 1x1 matrix:

'-0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(1.5707963268)+sin(x(2))*sin(1.5707963268)) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634)) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634)) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634)) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634)) -0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(0.0000000000)+sin(x(2))*sin(0.0000000000)) '

But i would like to remove the first and last ' ' to get this:

-0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(1.5707963268)+sin(x(2))*sin(1.5707963268)) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634)) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634)) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634)) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634)) -0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(0.0000000000)+sin(x(2))*sin(0.0000000000))

in order to use it later with fsolve.

Does anybody know how to do this?

[Stephen23]

"Does anybody know how to do this?"

The single quotes are not part of the text, they are simply artifacts of the display routine (indicating the text is a character vector). It is not possible to remove what is not even there. You are confusing text with code.

As Jan correctly wrote, most likely you could simply write a function in an Mfile and supply that name/function handle of that function to FSOLVE. Then you can simply avoid the indirection of importing text and fiddling around with STR2FUNC.

Answer 1

[Karim]

I would recommand to read the text file into a string array, this will ease the conversion into function. See below for a demonstration

% read the text file into a string array
F = readlines('equations list.txt')

F = 6×1 string array
    "-0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(1.5707963268)+sin(x(2))*sin(1.5707963268))"
    "-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634))"
    "-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634))"
    "-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634))"
    "-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634))"
    "-0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(0.0000000000)+sin(x(2))*sin(0.0000000000))"

% add '@(x)' to convert into functions
F = "@(x) " + F

F = 6×1 string array
    "@(x) -0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(1.5707963268)+sin(x(2))*sin(1.5707963268))"
    "@(x) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634))"
    "@(x) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634))"
    "@(x) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634))"
    "@(x) -0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634))"
    "@(x) -0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(0.0000000000)+sin(x(2))*sin(0.0000000000))"

% convert the strings into functions
F_eqn = cell(size(F));
for i = 1:length(F)
    F_eqn{i} = str2func(F(i));
end

% have a look at the content
F_eqn

F_eqn = 6×1 cell array
    {  @(x)-0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(1.5707963268)+sin(x(2))*sin(1.5707963268))}
    {@(x)-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634))}
    {  @(x)-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634))}
    {  @(x)-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(0.7853981634)+sin(x(2))*sin(0.7853981634))}
    {@(x)-0.0002578447+2*x(1)*0.7071067812*(0.0021272263)^2*(cos(x(2))*cos(-0.7853981634)+sin(x(2))*sin(-0.7853981634))}
    {  @(x)-0.0003646474+2*x(1)*1.0000000000*(0.0021272263)^2*(cos(x(2))*cos(0.0000000000)+sin(x(2))*sin(0.0000000000))}

% evaluate function 2 with random input
x_test = rand(2,1);
my_sol = F_eqn{2}(x_test)

my_sol = -2.5815e-04

Answer 2

[Jan]

The quotes are not part of the contents, but shown in the command window only to show, that this is a CHAR vector. Therefore there is no need to remove the quotes.

fsolve processes functions, not CHAR vectors. Instead of importing the file, it would be much easier to convert it to an m-function: Insert the formul here:

function y = fcn(x)
y = ... % your text here
end

and save this as fcn.m .