Problem in executing the code

%%  
clc;
clear;

%Q.) 7
%Evaluate integral of exp(-x)/sqrt(x) over [0,1].
%(a) Using a rectangular rule
%(b) Make a change of variables x = t^2 and use rectangular rule on new variable.

%After applying change of variables we get the integral to find out  equal
%to integral of exp(-x^2) over [-1,1].
syms f(x);
f(x)       =  exp(-x^2);
syms g(t);
g(t)       =  exp(-t)/t^(1/2);
a          =  -1;
b          =   1;
N          =  [5 10 20 50 100 200 500 1000];
exact_int  =  1.4936482656248540507989;      % exact value of integral evauated from wolfram alpha.
Ngrids     =  8;                             % Number of different grids
h          =  zeros(Ngrids,1);
rect_1     =  zeros(Ngrids,1);
rect_2     =  zeros(Ngrids,1);
for i     =  1  :  Ngrids
    h(i)=(b-a)/N(i);                  % Different-different grid spacing 
    x   = linspace(a,b,N(i)+1);       % Grid Points
    t   = linspace(a,b,N(i)+1);       % Grid Points
    y1  = 0.5*(x(1:N(i))+x(2:N(i)+1));% Midpoints of each panel  
    y2  = 0.5*(t(1:N(i))+t(2:N(i)+1));% Midpoints of each panel   
    rect_1(i)=h(i)*sum(f(y1));           % Rectangular rule
    rect_2(i)=h(i)*sum(g(y2));           % Rectangular rule after applying change of variables
end
error_rect_1      =  abs(double(rect_1     - exact_int));       % absolute error using Rectangular rule
error_rect_2      =  abs(double(rect_2     - exact_int));       % absolute error using Rectangular rule after applying change of variables

figure;
loglog(h,error_rect_1,'r','linewidth',1);
hold on
loglog(h,error_rect_2,'b','linewidth',1);
xlabel('Gridspacing');
ylabel('Error');
legend('Recangular rule' ,'Rectangular rule after applying change of variables','location','southeast','FontSize',7,...
       'FontWeight','bold','Color','y');

[Aman Gupta]

%%  
clc;
clear;

%Q.) 7
%Evaluate integral of exp(-x)/sqrt(x) over [0,1].
%(a) Using a rectangular rule
%(b) Make a change of variables x = t^2 and use rectangular rule on new variable.

%After applying change of variables we get the integral to find out  equal
%to integral of exp(-x^2) over [-1,1].
syms f(x);
f(x)       =  exp(-x^2);
syms g(t);
g(t)       =  exp(-t)/t^(1/2);
a          =  -1;
b          =   1;
c          =   0;
N          =  [5 10 20 50 100 200 500 1000];
exact_int  =  1.4936482656248540507989;      % exact value of integral evauated from wolfram alpha.
Ngrids     =  8;                             % Number of different grids
h1         =  zeros(Ngrids,1);
h2         =  zeros(Ngrids,1);
rect_1     =  zeros(Ngrids,1);
rect_2     =  zeros(Ngrids,1);
for i      =  1  :  Ngrids
    h1(i)=(b-a)/N(i);                     % Different-different grid spacing 
    h2(i)=(b-c)/N(i);
    x   = linspace(a,b,N(i)+1);           % Grid Points
    t   = linspace(c,b,N(i)+1);           % Grid Points
    y1  = 0.5*(x(1:N(i))+x(2:N(i)+1));    % Midpoints of each panel in  x(i)'s
    y2  =  0.5*(t(1:N(i))+t(2:N(i)+1));   % Midpoints of each panel in  t(i)'s
    rect_1(i)=h1(i)*sum(f(y1));           % Rectangular rule after applying change of variables
    rect_2(i)=h2(i)*sum(g(y2));           % Rectangular rule 
end
error_rect_1      =  abs(double(rect_1     - exact_int));       % absolute error using Rectangular rule after applying change of variables

error_rect_2      =  abs(double(rect_2     - exact_int));       % absolute error using Rectangular rule 
figure;
loglog(h1,error_rect_1,'r','linewidth',1);
hold on
loglog(h2,error_rect_2,'b','linewidth',1);
hold on
loglog(h1,h1.^2,'k');
hold on
loglog(h2,h2.^2,'g');
xlabel('Gridspacing');
ylabel('Error');
title('"Error vs GridSpacing" for Rectangular Rules with and Without changing of variables','FontSize',14,...
       'FontWeight','bold','Color','k');
legend('Recangular rule after applying change of variables' ,'Rectangular rule','h1^2','h2^2','location','southeast','FontSize',11,...
       'FontWeight','bold','Color','y');

[Aman Gupta]

The above code has run successfully, got the fault actually.