# Floats from bytes in Motoko
**URL:** https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595
**Category:** Language Support
**Tags:** Motoko
**Created:** [July 28, 2022, 2:14pm UTC](https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595 "2022-07-28T14:14:58Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@Gekctek](https://forum.dfinity.org/u/Gekctek)
#### Post date: [July 28, 2022, 2:14pm UTC](https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595/1 "2022-07-28T14:14:58Z")
I am currently trying to convert a byte array to a Float (16, 32 and 64 bit) without success. I understand the binary structure of a float but not sure how to translate it in motoko.
I don’t see any methods in the Float base module that would help and I’m not even sure where to look. Doesn’t seem like bitshifting out the components will help either but I could be missing something.
Any help would be great
---
### Author:  [@Gekctek](https://forum.dfinity.org/u/Gekctek)
#### Post date: [July 29, 2022, 5:17am UTC](https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595/2 "2022-07-29T05:17:31Z")
I think I figured it out using bitshifting, needed to approach it from a different angle
```auto
public func decodeFloat(bytes: [Nat8]) : ?Float {
var bits: Nat64 = Binary.BigEndian.toNat64(bytes);
let (exponentBitLength: Nat64, mantissaBitLength: Nat64) = switch(bytes.size()) {
case (2) {
(5: Nat64, 10: Nat64);
};
case (4) {
(8: Nat64, 23: Nat64);
};
case (8) {
(11: Nat64, 52: Nat64);
};
case (a) return null;
};
// Bitshift to get mantissa, exponent and sign bits
let mantissaBits: Nat64 = bits & (Nat64.pow(2, mantissaBitLength) - 1);
let exponentBits: Nat64 = (bits >> mantissaBitLength) & (Nat64.pow(2, exponentBitLength) - 1);
let signBits: Nat64 = (bits >> (mantissaBitLength + exponentBitLength)) & 0x01;
// Convert bits into numbers
let e: Int64 = Int64.pow(2, Int64.fromNat64(exponentBits) - ((Int64.fromNat64(Nat64.pow(2, exponentBitLength) / 2)) - 1));
let maxOffsetInverse: Float = Float.pow(2, Float.fromInt64(Int64.fromNat64(mantissaBitLength)) * -1);
let m: Float = 1.0 + (Float.fromInt64(Int64.fromNat64(mantissaBits)) * maxOffsetInverse);
var floatValue: Float = Float.fromInt64(e) * m;
// Make negative if sign bit is 1
if (signBits == 1) {
floatValue := Float.mul(floatValue, -1.0);
};
?floatValue;
}
```
BUT im still having issues with things like INFINITY and NaN, which dont seem to exist in Motoko.
Anyone have thoughts on those? not sure if it matters
---
### Author:  [@chenyan](https://forum.dfinity.org/u/chenyan)
#### Post date: [July 29, 2022, 6:39pm UTC](https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595/3 "2022-07-29T18:39:03Z")
Curious why you cannot pass `Float` directly as argument?
---
### Author:  [@skilesare](https://forum.dfinity.org/u/skilesare)
#### Post date: [July 29, 2022, 8:23pm UTC](https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595/4 "2022-07-29T20:23:56Z")
He’s building CBOR and Candid Interpreters for Motoko so we can use http\_outgoing\_request from a canister to call services on the IC use t-ECDSA signatures. 😬
---
### Author:  [@chenyan](https://forum.dfinity.org/u/chenyan)
#### Post date: [July 29, 2022, 9:19pm UTC](https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595/5 "2022-07-29T21:19:28Z")
Okay, then you can use `from_candid(blob) : ?Float`. Append the blob with prefix `DIDL\00\01\72` to indicate this is a float64 value.
---
### Author:  [@skilesare](https://forum.dfinity.org/u/skilesare)
#### Post date: [July 29, 2022, 9:33pm UTC](https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595/6 "2022-07-29T21:33:55Z")
Is there a list of those prefixes somewhere?
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### Author:  [@chenyan](https://forum.dfinity.org/u/chenyan)
#### Post date: [July 29, 2022, 9:43pm UTC](https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595/7 "2022-07-29T21:43:46Z")
Yes, it’s in the Candid spec: [candid/Candid.md at master · dfinity/candid · GitHub](https://github.com/dfinity/candid/blob/master/spec/Candid.md#binary-format)
---
### Author:  [@Gekctek](https://forum.dfinity.org/u/Gekctek)
#### Post date: [July 29, 2022, 10:15pm UTC](https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595/8 "2022-07-29T22:15:37Z")
I wonder how hard it would be to expose that float parsing functionality to Motoko itself
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### Author:  [@ggreif](https://forum.dfinity.org/u/ggreif)
#### Post date: [August 28, 2022, 12:11am UTC](https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595/9 "2022-08-28T00:11:11Z")
Generally the RTS can do a lot of stuff (it’s written in Rust). But it is a delicate game to only include things that are relevant for the broad community, as bloat will weigh heavy on every installed canister.
---
### Author:  [@Gekctek](https://forum.dfinity.org/u/Gekctek)
#### Post date: [August 30, 2022, 10:12pm UTC](https://forum.dfinity.org/t/floats-from-bytes-in-motoko/14595/10 "2022-08-30T22:12:52Z")
Because I was implementing byte encoding libraries, I went ahead and made a library for number encoding/extensions for Nat, Int and Float
> **[GitHub - Gekctek/motoko\_numbers: An extension to numbers in motoko](https://github.com/Gekctek/motoko_numbers)**
>
> An extension to numbers in motoko. Contribute to Gekctek/motoko\_numbers development by creating an account on GitHub.