Clarification questions

[infinite-pursuits]

Hi there,
I have 2 clarification questions

type CubicCircuit struct {
X frontend.Variable gnark:"x"
Y frontend.Variable gnark:",public"
}

1. I assume that I can't assign floats to X or Y? Instead of CubicCircuit{X: 3, Y: 35} I can't do CubicCircuit{X: 3.4, Y: 35.2} ?Currently getting this error when I assign floats "can’t set fr.Element from type float64".

2. What is the usual way to get around this in that case?

---

type VerifyCircuit struct {
W [][][]frontend.Variable gnark:"W"
B [][]frontend.Variable gnark:"B"
Cx []frontend.Variable gnark:",public"
Chidden_layer_size []frontend.Variable gnark:"Chidden_layer_size"
Actcodearray [][]frontend.Variable gnark:",public"
}

3. Here the size of all the slices are to be supplied by a json. I tried assigning []frontend.Variables to these variables. But when I do any operation on a value like Cx[1] I get a runtime error: index out of range. Is it necessary to put the size in the struct definition?

4. If not, then how do I deal with the error?

[ivokub]

1. You cannot assign floats to variables. The SNARK arithmetic usually happens in the scalar field of the underlying elliptic curve. We have emulated emulation for non-native fields, but not for floats.
2. I think there is not good option - you can try use field emulation with a good modulus and doing fixed-point arithmetic.
3. There are two things -- when compiling the circuit we need to know the sizes of the arrays. There are two options - either use fixed-size arrays or assign already initialised slice to circuit when compiling.