Why does it tell me that it exceeded the array? if you have more than what it supports in graphics?

Why does it tell me that it exceeded the array? I don't understand if I put more than 1000

I leave the error message that matlab tells me

<<<Error message>>>

Index exceeds matrix dimensions.
Error in arduinomatlab (line 29)
    v1(muestras)=(valor(1));

<<Error message>>

<<CODE>>

function arduinomatlab
global v1 v2
v1=zeros(1,100000);
v2=zeros(1,100000);
n=10;
delete(instrfind({'Port'},{'COM3'}));
s = serial('COM3','BaudRate',9600,'Terminator','CR/LF');
warning('off','MATLAB:serial:fscanf:unsuccessfulRead');
fopen(s);
muestras=1;
figure('Name','Captura');
xlabel('Muestras')
ylabel('Voltaje (V)')
title('Captura de voltaje en tiempo real con Arduino')
grid on
hold on
while muestras<=n
    ylim([0 15]);
    xlim([muestras-10 muestras+10]);
    valor=fscanf(s, '%d,%d')';
    
    v1(muestras)=(valor(1));
    v2(muestras)=(valor(2));
    plot(muestras, v1(muestras),'*-b');
    plot(muestras, v2(muestras),'*-r');
    drawnow
    muestras=muestras+1;
    
end
fclose(s);
delete(s);
clear s;
end

Answer 1

[Walter Roberson]

max_error = 10;
error_count = 0;
while muestras<=n && error_count < max_error
    ylim([0 15]);
    xlim([muestras-10 muestras+10]);
    thisline = fgetl(s);
    valor = sscanf(thisline, '%d,%d')';
    if length(valor) < 2
        error_count = error_count + 1;
        fprintf('warning #%d, line with unexpected content: "%s"\n', error_count, thisline);
    else
        v1(muestras)=(valor(1));
        v2(muestras)=(valor(2));
        plot(muestras, v1(muestras),'*-b');
        plot(muestras, v2(muestras),'*-r');
        drawnow
        muestras=muestras+1;
    end
end
if error_count >= max_error
    fprintf('Gave up because of too many errors on input\n');
end