Getting variable from a script into the function of another script

Hello I have a quick question. I am working on a sudoku solver that can take user input. I already have the solver script and the input script working independently, but I do not know how to reference variable from the input within the solver function. The following code is the solver code:

    function A=sudoku(M)
% M    = intial sudoku matrix, with zeros for empty entries
% Mout = solution as a 9x9 matrix if there is a unique solution, or
%        as a 9x9xN matrix if there are N solutions
% 
% % find the unique solution to this puzzle in a fraction of a second:
%
M = userInputData
%
% input checking:
if ~ismatrix(M)
    error('Input matrix must be two dimensional.')
end
if any((size(M)-[9 9])~=0)
    error('Input matrix must have nine rows and nine columns.')
end
if any(any(M~=floor(M))) || any(abs(M(:)-4.5)>4.5)
    error('Only integers from zero to nine are permitted as input.')
end
%
% ----------
%
% main program:
A=0*M; % list of solutions to puzzle so far
[M,imp,A]=recurse(M,A); %#ok (need this syntax for recursion)
if imp
    error('No solution.')
end
A=A(:,:,2:end);
return
%
% ----------
%
% recursive guess algorithm:
 function [M,imp,A]=recurse(M,A)
%clc;disp(M);pause(.1)
[M,imp]=deduce(M); % perform deterministic deductions
if imp % if impossible, quit
    return
end
z=find(~M(:)); % indices of unsolved entries
if isempty(z) % if solved
    A(:,:,end+1)=M;
    return
end
impall=zeros(1,9);
for v=1:9
    Q=M;
    Q(z(1))=v; % guess
    [Q,impall(v),A]=recurse(Q,A);
end
imp=all(impall);
M=Q;
return
%
% ----------
%
% deterministic logic algorithm:
function [M,imp]=deduce(M)
%clc;disp(M);pause(.1)
imp=0; % not impossible yet
% solve what you can by deterministic deduction (no guessing)
Mprev = 10*M; % solution at previous stage
while any(M(:)-Mprev(:)) % iterate until no longer changing
    Mprev=M;
    N=ones(9,9,9);
    % zero out untrue entries for input
    [r,c]=find(M);
    for n=1:length(r)
        N(r(n),c(n),:)=0;
        N(r(n),c(n),M(r(n),c(n)))=1;
    end
    if any(any(sum(N,3)<1))
        imp=1; % impossible flag (no solution)
        return
    end
    [r,c]=find(sum(N,3)<2); % solved entries
    for n=1:length(r)
        if any(any(sum(N,3)<1))
            imp=1; %impossible flag (no solution)
            return
        end
        v = find(N(r(n),c(n),:)); % value of the entry
        M(r(n),c(n)) = v; % make sure entry is recorded
        % clear value out of row
        N(:,c(n),v)=0;
        % clear value out of column
        N(r(n),:,v)=0;
        % top row & left column of box:
        br = floor((r(n)-.5)/3)*3+1;
        bc = floor((c(n)-.5)/3)*3+1;
        % clear value out of box:
        N(br:br+2,bc:bc+2,v)=0;
        % reset value into proper place:
        N(r(n),c(n),v)=1;
    end
    % for each entry, find lone possibilites and record
    for r=1:9
        for c=1:9
            v=find(N(r,c,:));
            if length(v)==1
                M(r,c)=v;
            end
        end
    end
    % for each row, find lone possibilities and record
    for r=1:9
        for v=1:9
            c=find(N(r,:,v));
            if length(c)==1
                M(r,c)=v;
            end
        end
    end
    % for each column, find lone possibilities and record
    for c=1:9
        for v=1:9
            r=find(N(:,c,v));
            if length(r)==1
                M(r,c)=v;
            end
        end
    end
    % for each box, find lone possibilities and record
    for r=[1 4 7]
        for c=[1 4 7]
            for v=1:9
                Q=N(r:r+2,c:c+2,v);
                [pr,pc]=find(Q);
                if length(pr)==1
                    M(r+pr-1,c+pc-1)=v;
                end
            end
        end
    end
end
return
end
 end
end

I got this code from the internet, but I need the user's input to associated to the variable M. Whenever I try to reference the variable before going into the function it never even executes the solver function. Does anyone know how I can go about getting the variable into the function. Thank You!

[Star Strider]

How are you calling the sudoku function in your main script?

Are you calling it at all?