Unable to perform assignment because the indices on the left side are not compatible with the size of the right side

%% function
syms x real 
f = x^3*551-x^2*4180+1.2030*10^4*x+4375;

A = readmatrix(char(File));  % matrix A double of 160x100   
B = zeros(160,100); % matrix B of 160x100
    
%% Solve function f to x with given y values from the matrix A and save in B

    parfor i=1:16000
 
        B(i)= double(solve(f==A(i),x));
        
    end 

Using the for loop the error does not occur. Can someone help me? How can I solve this?

Answer 1

[Matt J]

    parfor i=1:16000
 
        tmp=double(solve(f==A(i),x));
        
        if isempty(tmp), 
            warning 'No solutions found.'
            tmp=nan; 
        elseif ~isscalar(tmp)
             warning 'Multiple solutions found.'
            tmp=tmp(1); 
        end
        
        B(i)=tmp;
        
    end 

[Christine]

Thank you Matt J!