Add vDSP_vabsD

Author: ptoffy

README.md

@@ -56,7 +56,7 @@ The package is structured as follows:
         - [x] `vvpow` - Raise a vector to a power
         - [x] `vDSP_vclrD` - Clear a vector
         - [x] `vDSP_vfillD` - Fill a vector with a value
-        - [ ] `vDSP_vabsD` - Absolute value of a vector
+        - [x] `vDSP_vabsD` - Absolute value of a vector
         - [ ] `vDSP_vnegD` - Negate a vector
         - [ ] `vDSP_vsqD` - Square a vector
         - [ ] `vDSP_dotprD` - Dot product of two vectors

Sources/AccelerateLinux/VectorOps/VectorBasicOps.swift

@@ -1,7 +1,6 @@
 #if canImport(Accelerate)
 @_exported import Accelerate
 #else
-import FoundationEssentials
 
 /// Calculates the double-precision maximum value of a vector.
 /// - Parameters:
@@ -179,4 +178,25 @@ public func vDSP_vfillD(
         i += 1
     }
 }
+
+/// Calculates the absolute value of each element in the supplied double-precision vector using the specified stride.
+/// - Parameters:
+///   - __A: The input vector A.
+///   - __IA: The distance between the elements in the input vector A.
+///   - __C: On output, the absolute values of the elements in the input vector.
+///   - __IC: The distance between the elements in the output vector C.
+///   - __N: The number of elements that the function processes.
+public func vDSP_vabsD(
+    _ __A: UnsafePointer<Double>,
+    _ __IA: vDSP_Stride,
+    _ __C: UnsafeMutablePointer<Double>,
+    _ __IC: vDSP_Stride,
+    _ __N: vDSP_Length
+) {
+    var i = 0
+    while i < __N {
+        __C[i * __IC] = abs(__A[i * __IC])
+        i += 1
+    }
+}
 #endif

Tests/AccelerateLinuxTests/VectorTests/VectorBasicOpsTests.swift

@@ -171,4 +171,24 @@ struct VectorBasicOpsTests {
                 3.14,
             ])
     }
+
+    // https://developer.apple.com/documentation/accelerate/1449982-vdsp_vabsd
+    @Test("vDSP_vabsD")
+    func vDSP_vabsDTest() {
+        let stride = 1
+
+        let values: [Double] = [-1, 2, -3, 4, -5, 6, -7, 8]
+
+        let absoluteValues = [Double](unsafeUninitializedCapacity: values.count) { buffer, initializedCount in
+            vDSP_vabsD(
+                values, stride,
+                buffer.baseAddress!, stride,
+                vDSP_Length(values.count)
+            )
+
+            initializedCount = values.count
+        }
+
+        #expect(absoluteValues == [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0])
+    }
 }