BNNS random number generator for Double value types

Question

Created 1w

Replies 3

Boosts 0

Participants 3

I generate an array of random floats using the code shown below. However, I would like to do this with Double instead of Float. Are there any BNNS random number generators for double values, something like BNNSRandomFillUniformDouble? If not, is there a way I can convert BNNSNDArrayDescriptor from float to double?

import Accelerate

let n = 100_000_000

let result = Array<Float>(unsafeUninitializedCapacity: n) { buffer, initCount in

    var descriptor = BNNSNDArrayDescriptor(data: buffer, shape: .vector(n))!
    let randomGenerator = BNNSCreateRandomGenerator(BNNSRandomGeneratorMethodAES_CTR, nil)

    BNNSRandomFillUniformFloat(randomGenerator, &descriptor, 0, 1)

    initCount = n
}

Boost

Answer 1

DTS Engineer OP

Apple

1w

Hello,

I'm not aware of a BNNSRandomFillUniformDouble, which is better than trying to workaround Swift type-safety.

What is the use case?

Please consider sending us an enhancement request detailing the use case with the Feedback Assistant.

1

Answer 2

Engineer OP

Apple

6d

To confirm, there's no Double support for BNNS random fill.

vDSP has very fast single- to double-precision conversion. The C API function is vDSP_vspdp and the Swift version is vDSP.convertElements

0

Answer 3

wigging OP

6d

I updated my example with vDSP.convertElements but this requires two arrays which are result and resultDouble. Is there a way to do this with just one array instead of two?

import Accelerate

let n = 100_000_000

let result = Array<Float>(unsafeUninitializedCapacity: n) { buffer, initCount in

    var descriptor = BNNSNDArrayDescriptor(data: buffer, shape: .vector(n))!
    let randomGenerator = BNNSCreateRandomGenerator(BNNSRandomGeneratorMethodAES_CTR, nil)

    BNNSRandomFillUniformFloat(randomGenerator, &descriptor, 0, 1)

    initCount = n
}

var resultDouble = [Double](repeating: 0, count: n)
vDSP.convertElements(of: result, to: &resultDouble)

0