Matlab does not seem to recognise my inputted commands

I am currently writing a set of codes but i cannot get Matlab to recognise that i have defined values for t. I have been told to use the "interpl" command but that doesn't seem to work either so i'm unsure how to debug this.

Here are my codes:

This is the file named daisyworld1

Lt=linspace(0,5);    %generate t for L

L=5*Lt+2;    %luminosity function

f=interpl(Lt,L,t);    %interpolate the data set (Lt,L) at time t

function dydt =daisyworld1(t,y,Lt,L);

dydt = [0;0];

A=((1-y(1)-y(2))*0.5)+(y(1)*0.25)+(y(2)*0.75);  %albedo

S=917;   %constant solar energy

Z=5.67*10^(-8);  %Stefan-Boltzmann constant;

Te=((((S*L)/Z)*(1-A)).^(1/4))-273; %plantary temperature

B=1-0.003265*((22.5-Te).^2);  %beta value, local temperature function

g=0.2; %x-value

dydt(1)=y(1)*(( (1-y(1)-y(2)) *B)-g);

dydt(2)=y(2)*(( (1-y(1)-y(2)) *B)-g);

And this is the code for solving it using ode45

t0=0; % Start time

tf=0.5; % End time

Lt=linspace(0,5,25);    %generate t for L

L=5*Lt+2;    %luminosity function

L=interpl(Lt,L,t);    %interpolate the data set (Lt,L) at time t

options=odeset('RelTol', 1e-4);% Sets the error tolerance of the ODE solver

aw=0.4; % Initial white daisy area

ab=0.2; % Initial black daisy area

[t, y]=ode45(@(t,y)daisyworld1(t,y,Lt,L),[aw ab],options); % Solves the equations

plot(t,y) % Plots the daisy area coverage against time

% Blue line is white daisies

% Green line is black daisies

The error message i keep getting is

Undefined function or variable 't'.

Error in daisyworldode45 (line 11)
L=interpl(Lt,L,t);    %interpolate the data set (Lt,L) at time t

I am trying to plot the coverage of daisies against Luminosity which i am using an increasing function of time for.

Any help would be much appreciated, thank you.

Answer 1

[Thorsten]

You have to define t before you can use it

 t = ... % whatever you need
 L = interpl(Lt,L,t);

Answer 2

[Walter Roberson]

You seem to have three lines of code before you define your function "daisyworld1". That is a problem.

[Kirsty James]

Hi, I have tried putting those lines of coding beneath defining the function and i still get the same error code of

daisyworldode45 Undefined function or variable 't'.

Error in daisyworldode45 (line 11) L=interpl(Lt,L,t); %interpolate the data set (Lt,L) at time t

When i run daisyworldode45