Hi there,

I am new to julia. I am trying to write a function to solve tridiagonal matrix system by Thomas Algorithm

Here is my code

```
function TDMA(a,b,c,D)
# Thomas Algorithm
# Vectors a,b,c have the same length
# Should have a[1]=0 and c[n]=0
# A*x = D
# [b[1] c[1] ] [ x[1] ] [ D[1] ]
# [a[2] b[2] c[2] ] [ x[2] ] [ D[2] ]
# [ ... ... ... ] [ ... ] = [ ... ]
# [ a[n-1] b[n-1] c[n-1]] [x[n-1]] [D[n-1]]
# [ a[n] b[n] ] [ x[n] ] [ D[n] ]
x = zeros(length(D),1)
d = D
n = length(D)
w = zeros(n,1)
for i = 2:n
w[i] = a[i]/b[i-1]
b[i] = b[i] - w[i]*c[i-1]
d[i] = d[i] - w[i]*d[i-1]
end
x[n] = d[n]/b[n]
for k = 1:n-1
x[n-k] = (d[n-k]-c[n-k]*x[n-k+1])/b[n-k]
end
x
end
```

I am testing it by this example

```
A =
[1 2 0;
4 5 6;
0 1 2]
Y = [1; 3; 4]
```

with

```
a = [0 4 1]
b = [1 5 2]
c = [2 6 0]
```

to be the arguments.

The build-in function

```
A\Y
```

gives the solution

```
-3.333333333333333
2.1666666666666665
0.9166666666666666
```

Howevery, when I try to use my TDMA to solve the equation, it comes error

```
TDMA(a,b,c,Y)
InexactError: Int64(4.545454545454545)
Stacktrace:
[1] Type at ./float.jl:703 [inlined]
[2] convert at ./number.jl:7 [inlined]
[3] setindex! at ./array.jl:767 [inlined]
[4] TDMA(::Array{Int64,2}, ::Array{Int64,2}, ::Array{Int64,2}, ::Array{Int64,1}) at ./In[13]:17
[5] top-level scope at In[14]:1
```

Can anyone help me with this?

Thanks