Why is my plot plotting blank?

clear all
close all

%DEFINING THE GRID (MESH) AND SIZE OF THE DOMAIN
L = 50; %Length of the vertical rock section (m)(use meter, kelvin, second always)
dz = 0.1; % size of the elements (m)
N = L/dz+1; % Number of nodes in the rock column

%DEFINING THE PHYSICAL PROPERTIES
K = 1.8; %Thermal conductivity of the rocks
Cp = 840 %specific heat of the rocks
rho = 3000; %density of the rocks
kappa = K/(Cp*rho); %Diffusivity of the rocks

%INITIALIZE THE VARIABLES 
time = 0; %I define the initial time
Tbot = 140;
Tbotnew = 140;
Ttop = 122; %Initial temperature, in degrees centigrade (C)
Ttopnew = linspace(Ttop,Tbot,N); %Initialize the new temperature array

%Plot initial T conditions
x= 1:N:50
y= Ttopnew
plot(x,y,'r');
    xlabel('Depth of rock column (m)')
    ylabel('Temperature (C)')

[Stephen23]

Please edit your question and format the code correctly using the {} Code button that you will find above the textbox.

Answer 1

[Jan]

You N is 501. Then x= 1:N:50 let x be the scalar 1. Inconsequence the plot use one x value only and when I run your code I see a vertical line, as expected.

When you omit the evil clear all you can use the debugger to step through the code line by line.