Scilab plotting functions with if

Question

I have a problen in scilab How can I plot functions containing if and < like

function y = alpha(t)
   if (t < 227.8) then 
       y = 0.75;
   elseif (t < 300) then
       y = 2.8 - 0.009 .* t;
   else
       y = 0.1;
   end   
endfunction

and

function [r]=minus_alpha(t)
    r = 1 - alpha(t)
endfunction

When I use

x = linspace(0,300)
plot(x, alpha(x))

I got the error message

WARNING: Transposing row vector X to get compatible dimensions
plot2d: falsche Größe für Eingangsargument: inkompatible Größen.
Error 999 : in plot2d called by plot

Sorry for german mix. Thank you.

Answer 1

If you check the output of your alpha(x), you will see that it is just a scalar (not a vector). I guess you wanted something like this, so it's necessary to iterate through t to compute each value of y based on the value of t:

clc;
clear;
function y = alpha(t)
    for i=1:size(t,"*") 
        if t(i) < 227.8 then 
            y(i) = 0.75;
        elseif t(i) < 300 then
            y(i) = 2.8 - 0.009 * t(i);
        else
            y(i) = 0.1;
        end  
    end 
endfunction

x = linspace(0,300);
plot2d(x,alpha(x));

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