Index in position 1 is invalid Problem

clear all
close all 
clc 

h = input('Enter the step size: '); %240
tf = input('Final Value: '); %480

t = 0:h:tf
th = zeros(1,length(t))

th(1) = input('Enter the initial value: '); %1200
fun = input("Enter the function with respect to th: "); %((-2.2067.*(10.^-12)).*((th.^4)-(81.*10^8)))

k_1 = fun(t(1), th(1))

Dear altruist,

This is my code, but it tells me that: "Index in position 1 is invalid. Array indices must be positive integers or logical

values."

Kindly help me with this.

Answer 1

[Eric Delgado]

Try this...

x = [0,240,480];
y = [1200,0,0];

Fcn_AddThings = str2func('@(x,y) x.^2 - 2*y');
Fcn_AddThings(x, y)

ans = 1×3

-2400 57600 230400

Fcn_AddThings(x(1), y(1))

ans = -2400

Looking at your example, you can replace str2fun for input - see the image below.