Could someone please optimize this code?

Could someone please optimize this code?

My code:

v0 = 10
gamma = 0.1
for k=1:101
    theta = 0.8444 * pi/4 + (k-51)*0.0001;
    dt = 0.0000001;
    x = 0;
    y = 0;
    vx = v0 * cos(theta);
    vy = v0 * sin(theta);
    x = x + dt * vx;
    y = y + dt * vy;
    while (y>0)
        v = sqrt(vx*vx+vy*vy);
        vx = vx - dt * gamma * vx;
        vy = vy - dt * 9.81 - dt * gamma * vx;
        x = x + dt * vx;
        y = y + dt * vy;
    end;
    t(k) = theta
    a(k) = x
end;
plot(a)
[vv, jv] = max(a)
t(jv) / (pi/4)

[John D'Errico]

It can be terribly difficult to optimize code if we are not told what the code is supposed to do. A few words of explanation would be a great help there.

[Adam Danz]

Original question by OP in case it is deleted (this user has deleted many questions after being answered).

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Could someone please optimize this code?

My code:

v0 = 10
gamma = 0.1
for k=1:101
    theta = 0.8444 * pi/4 + (k-51)*0.0001;
    dt = 0.0000001;
    x = 0;
    y = 0;
    vx = v0 * cos(theta);
    vy = v0 * sin(theta);
    x = x + dt * vx;
    y = y + dt * vy;
    while (y>0)
        v = sqrt(vx*vx+vy*vy);
        vx = vx - dt * gamma * vx;
        vy = vy - dt * 9.81 - dt * gamma * vx;
        x = x + dt * vx;
        y = y + dt * vy;
    end;
    t(k) = theta
    a(k) = x
end;
plot(a)
[vv, jv] = max(a)
t(jv) / (pi/4)

Answer 1

[Bob Thompson]

I don't know about 'optimized,' but I'm pretty sure you can remove the entire for loop by vectorizing. Also, suppressing your values will actually do a surprising amount to speed up run time. Anything visual takes a lot more time and power to output, even just numbers and letters.

v0 = 10;
gamma = 0.1;
range = (-50:50);
theta = 0.8444 * pi/4 + range.*0.0001;
dt = 0.0000001;
x = 0;
y = 0;
vx = v0 * cos(theta);
vy = v0 * sin(theta);
x = x + dt * vx;
y = y + dt * vy;
while y>0
    v = sqrt(vx*vx+vy*vy); % What does this do? It isn't used anywhere
    vx = vx - dt * gamma * vx;
    vy = vy - dt * 9.81 - dt * gamma * vx;
    x = x + dt * vx;
    y = y + dt * vy;
end
plot(x)
[vv, jv] = max(x);
t(jv) ./ (pi/4);

I suspect part of the problem is that your code doesn't ever actually produce a negative value for y. The first value is slightly >0, but after that all you're doing is adding more positive values.

[The Merchant]

What value does t(jv) ./ (pi/4) output for you?

My computer is wooden, so it hasn't stopped running for me...

[The Merchant]

I get the following error:

Unrecognized function or variable 't'.

[Bob Thompson]

I never got to t because the while loop was always positive and never stopped running. I would agree with the error that it is undefined.