This is a toy stochastic gradient system which can have bistability in some conditions. Model specification: $$U = x^4 + y^4 + axy + bx + cy$$ $$dx/dt = - \partial U/ \partial x + \sigma dW/dt = - 4x^3 - ay - b + \sigma dW/dt$$ $$dy/dt = - \partial U/ \partial y + \sigma dW/dt = - 4y^3 - ax - c + \sigma dW/dt$$

## Arguments

- initial, parameter
Two sets of parameters.

`initial`

contains the initial value of`x`

and`y`

;`parameter`

contains`a,b,c`

, which control the shape of the potential landscape, and`sigmasq`

, which is the square of \(\sigma\) and controls the amplitude of noise.- length
The length of simulation.

- stepsize
The step size used in the Euler method.

- seed
The initial seed that will be passed to

`set.seed()`

function.