Array indices must be positive integers or logical values.

function [z]=phi(x)
%Determine phi(x) using the formulas provided
%2/25/21
%AE 227

a=0.4361836;
b=0.1201676;
c=0.937298;
r=exp(-.5*(x^2))/sqrt(2*pi);
t=1/(1+(0.3326*x));
z=0.5-r(a*t-b(t^2)+c(t^3));
end

Answer 1

[KSSV]

function [z]=phi(x)
%Determine phi(x) using the formulas provided
%2/25/21
%AE 227

a=0.4361836;
b=0.1201676;
c=0.937298;
r=exp(-.5*(x.^2))/sqrt(2*pi);
t=1./(1+(0.3326*x));
z=0.5-r.*(a*t-b*(t.^2)+c*(t.^3));  % <--- change in this line
end

[dylan stephens]

why are you placing a . after r and t?

[dylan stephens]

I was able to get it to work with

z=0.5-r*(a*t-b*(t^2)+c*(t^3));

[KSSV]

why are you placing a . after r and t?

Read about element by element operations.

I was able to get it to work with z=0.5-r*(a*t-b*(t^2)+c*(t^3));

You cannot work with that, if x is a vector.

[dylan stephens]

Would you be able to provide a link to element by element operations unable to find it in my book.

[KSSV]

https://in.mathworks.com/help/matlab/matlab_prog/array-vs-matrix-operations.html