# Dv/dt = (v+1)/10v^2 Euler's method

## Homework Statement

dv/dt = (v+1)/10v^2 Euler method delta t = .5, t =0 and v = 1, to find v(4)

## Homework Equations

I'm using v = v(old) + (stepsize)(dv/dt) I'm just wondering if anyone can confirm my results. My teacher said that although this seems easy over half the hw will be wrong because of calculator mistakes.

## The Attempt at a Solution

I know it is boring but could someone double check me? Maybe put it in wolfram Idk exactly how to do it.THanks Or maybe someone has a program.

For my final calculation I got v(4) = 1.731618162

Man I hope that is OK

vela
Staff Emeritus
Homework Helper
I got v(4) = 1.5740 using a spreadsheet. Just to make sure, it's ##\frac{dv}{dt} = \frac{v+1}{10v^2}## and v(0)=1, right?

The exact question is
Use Euler's method with ##\frac{dv}{dt} = \frac{v+1}{10v^2}## and delta t = 0.5, starting at t =0 and v = 1, to find v(4).
So yeah. But did you use the right step size.I will give you a couple values I want to see if I was doing it right but went wrong.

So for t = 1.0 I have v = 1.18677686
t = 2.0 I have v = 1.406046194
t = 3.0 I have v = 1.524220178
Do any of those look OK?
Thanks

vela
Staff Emeritus
Homework Helper
Your result for t=1.0 matches mine, but the others don't.

Figures.
So dv/dt for 1.0 I have .1552624125 is that what you got?

vela
Staff Emeritus
Homework Helper
Yes.

Dude I GOT IT! Whohoo. Thanks. It is so funny that something that seems very simple ends up being clustered for me.

If you did it on a spread sheet and it was easy can you punch in another one for me? This is the last one I had from my hw.
If not and it is a drag to do that's OK.

But here it is just in case.

y' = xy -x^2 and y(0) = 1 they want y(1).

I got 3.08106496

vela
Staff Emeritus
Homework Helper
What step size?

With a step size of 0.1, I get about 1.217, and the actual value is about 1.238. It looks like your number is a bit off.

Last edited:
Step size is 0.2
Sorry I left that out.

vela
Staff Emeritus
Homework Helper
With a step size of 0.2, I get y(1)=1.195.

I get that but for when x = .8

Yours started at 0? Y(0) = 1?

So my y(1) = 1.233930342

D H
Staff Emeritus