Matlab code help!

I keep getting incorrect output values.

Here is my code:

function [erf_trapezoid, erf_GL3] = student_solution(x)

% Define integrand

integrand = @(x) (2/sqrt(pi))*exp(-x.^2);

% Preallocate output vectors

erf_trapezoid = zeros(length(x),1);

erf_GL3 = zeros(length(x),1);

% Define coefficients and arguments for Gauss-Legendre quadrature

c = [5/9 8/9 5/9];

x_arg = [-sqrt(3/5) 0 sqrt(3/5)];

% Compute erf using composite trapezoid rule and Gauss-Legendre quadrature

for i = 1:length(x)

x_val = [0 x(i)]'; % Include endpoints for trapezoid rule

y_val = integrand(x_val); % Evaluate integrand at x=0 and x(i)

erf_trapezoid(i) = trapz(x_val, y_val); % Use trapezoid rule to estimate integral

x_d = (x_arg+1)*x(i)/2; % Compute shifted x values for Gauss-Legendre quadrature

y_d = integrand(x_d); % Evaluate integrand at shifted x values

erf_GL3(i) = x(i)/2*sum(c.*y_d); % Use Gauss-Legendre quadrature to estimate integral

end

end

Vrite a function that receives the following single input: 1. A column vector of one or more x values at which erf(x) is to be computed. four function should return the following outputs (in order, column vectors when input x is a vector): 1. The estimate(s) for erf(x) calculated using composite trapezoid rule between 0 and each of the elements in x. Evaluate the integrand at 0 and at the input x-values to compute y-values for the trapezoid rule. 2. The estimate(s) of erf(x) calculated using three-point Gauss-Legendre quadrature. Work by hand to develop the shifted integrand (in terms of xd ) and use the appropriate constants and function evaluations