I am trying to accomplish this same task using the find() command but I'm not sure how.

clear all
n = 1
for k = 0:.1:6
    x(n) = k
    if (2 <= x(n))&&(x(n) <= 4)
        y(n) = 2*k
    else
        y(n) = -5*k
    end
    n=n+1
end
plot(x,y)

Answer 1

[Star Strider]

Here is a version that uses a logical vector in place of the find function:

x = 0:0.1:6;
y = -5*x;
lv = (2 <= x) & (x <= 4);                       % Logical Vector Of ‘x’ Elements Satisfying Conditions
y(lv) = 2*x(lv ~= 0);

figure
plot(x,y)

A version using the find function would be:

x = 0:0.1:6;
y = -5*x;
idx = find((2 <= x) & (x <= 4));                % Index Vector Of ‘x’ Elements Satisfying Conditions
y(idx) = 2*x(idx);

figure
plot(x,y)

[James Raj]

Thanks!

[Star Strider]

As always, my pleasure!

Answer 2

[Walter Roberson]

Hint:

t = 1:1.5:20;
output = zeros(size(t));
ind = find(t >= 3 & t <= 9);
output(ind) = sin(t(ind));
ind = setdiff(1:numel(t), ind);
output(ind) = -cos(t(ind));