Hello, I am a complete Julia beginner and am working through Example 2: Solving Systems of Equations and Defining Parameterized Functions, trying to adapt my food-chain formulas to Julia. I have also watched Intro to solving differential equations in Julia.

I am using Julia 1.0 on Windows 10, and have updated all packages and have DifferentialEquations (also updated) installed.

The start equations and parameters are:

```
du[1] = u1*(1-u1)-(1/e)*y2*x2*u1^(1-q)/(u012^(1+q)+u1^(q+1))*u2
du[2] = y2*x2*u1^(1+q)/(u012^(1+q)+u1^(1+q))*u2-(1/e)*y3*x3*u2^(1+q)/(u023^(1+q)+u2^(1+q))*u3-x2*u2
du[3] = y3*x3*u2^(1+q)/(u023^(1+q)+u2^(1+q))*u3-x3*u3
```

Initial values = u1= 0.01, u2 = 0.01, u3 = 0.01

e = 1

y2 = 2

x2 = 3

q = 4

u012 = 5

y3 = 6

x3 = 7

u023 = 8

t-max = 10000

t-interval = 0.05

Based on the tutorial my code currently looks like this:

using DifferentialEquations

function Bio(du,u,p,t)

du[1] = u[1]*(1-u[1])-(1/[1])*[2]*[3]*u[1]^(1-[4])/([5]^(1+[4])u[1]^([4]+1))*u[2]
du[2] = [2]*[3]

*u[1]^(1+[4])/([5]^(1+[4])+u[1]^(1+[4]))*[7]*u[2]^(1+[4])/([8]^(1+[4])+u[2]^(1+[4]))*u[3]-[3]

*u[2]-(1/[1])*[6]*u[2]*

du[3] = [6][7]*u[2]^(1+[4])/([8]^(1+[4])+u[2]^(1+[4]))*u[3]-[7]*u[3]

du[3] = [6]

end

u0 = [0.01,0.01,0.01]

p=(1,2.009,0.4,5,0.08,0,0.16129,0.5)

tspan = (0.01, 10000)

prob=ODEProblem(Bio,u0,tspan,p)

sol=solve(prob)

I generate an error once *sol=solve(prob)* runs.

ERROR: MethodError: no method matching -(::Int32, ::Array{Int32,1})

Closest candidates are:

-(::Union{Int128, Int16, Int32, Int64, Int8, UInt128, UInt16, UInt32, UInt64, UInt8}) at int.jl:51

-(::T<:Union{Int128, Int16, Int32, Int64, Int8, UInt128, UInt16, UInt32, UInt64, UInt8}, ::T<:Union{Int128, Int16, Int32, Int64, Int8, UInt128, UInt16, UInt32, UInt64, UInt8}) where T<:Union{Int128, Int16, Int32, Int64, Int8, UInt128, UInt16, UInt32, UInt64, UInt8} at int.jl:52

-(::Union{Int16, Int32, Int8}, ::BigInt) at gmp.jl:458

â€¦

Stacktrace:

[1] Bio(::Array{Float64,1}, ::Array{Float64,1}, ::Tuple{Int32,Float64,Float64,Int32,Float64,Int32,Float64,Float64}, ::Float64) at .\REPL[12]:2

[2] (::ODEFunction{true,typeof(Bio),LinearAlgebra.UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing})(::Array{Float64,1}, ::Array{Float64,1}, ::Vararg{Any,N} where N) at C:\Users\Helga.julia\packages\DiffEqBase\mcoTV\src\diffeqfunction.jl:106

[3] initialize!..

â€¦ followed by 5 pages of text.

What am I doing wrong? And how may I incorporate time intervals of 0.05? Any assistant/advice would be greatly appreciated.