# Recursive filters Perform two-pole two-zero recursive filtering on a vector. ## Topics ### Vector-to-Vector Recursive Filtering on Real Vectors [`static func twoPoleTwoZeroFilter(U, coefficients: (Double, Double, Double, Double, Double)) -> [Double]`](/documentation/Accelerate/vDSP/twoPoleTwoZeroFilter(_:coefficients:)-8oaux) Returns the result of double-precision, two-pole, two-zero recursive filtering. [`static func twoPoleTwoZeroFilter(U, coefficients: (Float, Float, Float, Float, Float)) -> [Float]`](/documentation/Accelerate/vDSP/twoPoleTwoZeroFilter(_:coefficients:)-3jbcg) Returns the result of single-precision, two-pole, two-zero recursive filtering. [`static func twoPoleTwoZeroFilter(U, coefficients: (Double, Double, Double, Double, Double), result: inout V)`](/documentation/Accelerate/vDSP/twoPoleTwoZeroFilter(_:coefficients:result:)-fe5l) Performs double-precision, two-pole, two-zero recursive filtering. [`static func twoPoleTwoZeroFilter(U, coefficients: (Float, Float, Float, Float, Float), result: inout V)`](/documentation/Accelerate/vDSP/twoPoleTwoZeroFilter(_:coefficients:result:)-gq5l) Performs single-precision, two-pole, two-zero recursive filtering. [`extern void vDSP_deq22(const float *__A, vDSP_Stride __IA, const float *__B, float *__C, vDSP_Stride __IC, vDSP_Length __N);`](/documentation/Accelerate/vDSP_deq22) Performs two-pole two-zero recursive filtering on a single-precision vector. [`extern void vDSP_deq22D(const double *__A, vDSP_Stride __IA, const double *__B, double *__C, vDSP_Stride __IC, vDSP_Length __N);`](/documentation/Accelerate/vDSP_deq22D) Performs two-pole two-zero recursive filtering on a double-precision vector. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)