I have got "Error using serial/fopen (line 72) Open failed: Port: COM5 is not available. No ports are available. Use INSTRFIND to determine if other instrument objects are connected to the requested device. Error in viread (line 5) fopen (comport);"

my code body is

clear all;
clc;
close all;
comport=serial('COM5','Baudrate',9600);
fopen (comport);
x=0;
while(x<100)
    x=x+1;
    v1(x)=fscanf(comport, '%d');
    plot(v1,'r--','linewidth',3)
    grid on;
    hold on;
end
fclose(comport);
delete(comport);

[Walter Roberson]

Is the arduino connected to COM5?

What happened when you use instrfind to find out what was already in use?