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vDSP Vector-To-Scalar Operations Reference

Overview

This document describes the C API for the vDSP functions that receive a vector as input and compute scalars as output. Examples of such operations include calculating the dot product of a vector, or finding the minimum or maximum of a vector.

Functions by Task

Calculating Dot Products

• vDSP_dotpr
• vDSP_dotprD
• vDSP_zdotpr
• vDSP_zdotprD
• vDSP_zidotpr
• vDSP_zidotprD
• vDSP_zrdotpr
• vDSP_zrdotprD

Finding Maximums

• vDSP_maxv
• vDSP_maxvD
• vDSP_maxvi
• vDSP_maxviD
• vDSP_maxmgv
• vDSP_maxmgvD
• vDSP_maxmgvi
• vDSP_maxmgviD

Finding Minimums

• vDSP_minv
• vDSP_minvD
• vDSP_minvi
• vDSP_minviD
• vDSP_minmgv
• vDSP_minmgvD
• vDSP_minmgvi
• vDSP_minmgviD

Calculating Means

• vDSP_meanv
• vDSP_meanvD
• vDSP_meamgv
• vDSP_meamgvD
• vDSP_measqv
• vDSP_measqvD
• vDSP_mvessq
• vDSP_mvessqD
• vDSP_rmsqv
• vDSP_rmsqvD

Summing Vectors

• vDSP_sve
• vDSP_sveD
• vDSP_svemg
• vDSP_svemgD
• vDSP_svesq
• vDSP_svesqD
• vDSP_svs
• vDSP_svsD

Functions

vDSP_dotpr

Computes the dot or scalar product of vectors A and B and leaves the result in scalar C; single precision.

   void vDSP_dotpr (const float A[],
   vDSP_Stride I,
   const float B[],
   vDSP_Stride J,
   float * C,
   vDSP_Length N);

Discussion

This performs the operation

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_dotprD

Computes the dot or scalar product of vectors A and B and leaves the result in scalar C; double precision.

   void vDSP_dotprD (const double A[],
   vDSP_Stride I,
   const double B[],
   vDSP_Stride J,
   double * C,
   vDSP_Length N);

Discussion

This performs the operation

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_maxmgv

Vector maximum magnitude; single precision.

   void vDSP_maxmgv (const float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input vector. If passed a vector with no elements, this function returns a value of 0 in C.

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

*C = 0;

for (n = 0; n < N; ++n)

    if (*C < abs(A[n*I]))

        *C = abs(A[n*I]);

Finds the element with the greatest magnitude in vector A and copies this value to scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_maxmgvD

Vector maximum magnitude; double precision.

   void vDSP_maxmgvD (const double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input vector. If passed a vector with no elements, this function returns a value of 0 in C.

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

*C = 0;

for (n = 0; n < N; ++n)

    if (*C < abs(A[n*I]))

        *C = abs(A[n*I]);

Finds the element with the greatest magnitude in vector A and copies this value to scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_maxmgvi

Vector maximum magnitude with index; single precision.

   void vDSP_maxmgvi (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length * IC,
   vDSP_Length N);

Parameters

A

Single-precision real input vector. If passed a vector with no elements, this function returns a value of 0 in *C, and the value returned in IC is undefined.

I

Stride for A

C

Output scalar

IC

Output scalar index

N

Count

Discussion

This performs the operation

*C = 0;

for (n = 0; n < N; ++n)

{

    if (*C < abs(A[n*I]))

    {

        *C = abs(A[n*I]);

        *IC = n*I;

    }

}

Copies the element with the greatest magnitude from real vector A to real scalar C, and writes its zero-based index to integer scalar IC. The index is the actual array index, not the pre-stride index. If vector A contains more than one instance of the maximum magnitude, IC contains the index of the first instance.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_maxmgviD

Vector maximum magnitude with index; double precision.

   void vDSP_maxmgviD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length * IC,
   vDSP_Length N);

Parameters

A

Double-precision real input vector. If passed a vector with no elements, this function returns a value of 0 in *C. The value returned in IC is undefined.

I

Stride for A

C

Output scalar

IC

Output scalar

N

Count

Discussion

This performs the operation

*C = 0;

for (n = 0; n < N; ++n)

{

    if (*C < abs(A[n*I]))

    {

        *C = abs(A[n*I]);

        *IC = n*I;

    }

}

Copies the element with the greatest magnitude from real vector A to real scalar C, and writes its zero-based index to integer scalar IC. The index is the actual array index, not the pre-stride index. If vector A contains more than one instance of the maximum magnitude, IC contains the index of the first instance.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_maxv

Vector maximum value; single precision.

   void vDSP_maxv (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input vector.

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

*C = -INFINITY;

for (n = 0; n < N; ++n)

    if (*C < A[n*I])

        *C = A[n*I];

Finds the element with the greatest value in vector A and copies this value to scalar C. If A has length of 0, this function returns -INFINITY.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_maxvD

Vector maximum value; double precision.

   void vDSP_maxvD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

*C = -INFINITY;

for (n = 0; n < N; ++n)

    if (*C < A[n*I])

        *C = A[n*I];

Finds the element with the greatest value in vector A and copies this value to scalar C. If A has length of 0, this function returns -INFINITY.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_maxvi

Vector maximum value with index; single precision.

   void vDSP_maxvi (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length * IC,
   vDSP_Length N);

Parameters

A

Single-precision real input vector.

I

Stride for A

C

Output scalar

IC

Output scalar index

N

Count

Discussion

This performs the operation

*C = -INFINITY;

for (n = 0; n < N; ++n)

{

    if (*C < A[n * I])

    {

        *C = A[n * I];

        *IC = n * I;

    }

}

Copies the element with the greatest value from real vector A to real scalar C, and writes its zero-based index to integer scalar IC. The index is the actual array index, not the pre-stride index. If vector A contains more than one instance of the maximum value, IC contains the index of the first instance. If A is vector with no elements, this function returns a value of -infinity in C and *IC is undetermined.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_maxviD

Vector maximum value with index; double precision.

   void vDSP_maxviD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length * IC,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Output scalar

IC

Output scalar

N

Count

Discussion

This performs the operation

*C = -INFINITY;

for (n = 0; n < N; ++n)

{

    if (*C < A[n * I])

    {

        *C = A[n * I];

        *IC = n * I;

    }

}

Copies the element with the greatest value from real vector A to real scalar C, and writes its zero-based index to integer scalar IC. The index is the actual array index, not the pre-stride index. If vector A contains more than one instance of the maximum value, IC contains the index of the first instance. If A is vector with no elements, this function returns a value of -infinity in C and *IC is undetermined.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_meamgv

Vector mean magnitude; single precision.

   void vDSP_meamgv (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input vector

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the mean of the magnitudes of elements of vector A and stores this value in scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_meamgvD

Vector mean magnitude; double precision.

   void vDSP_meamgvD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the mean of the magnitudes of elements of vector A and stores this value in scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_meanv

Vector mean value; single precision.

   void vDSP_meanv (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input vector. If passed an array of length 0, this function returns a NaN.

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the mean value of the elements of vector A and stores this value in scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_meanvD

Vector mean value; double precision.

   void vDSP_meanvD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the mean value of the elements of vector A and stores this value in scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_measqv

Vector mean square value; single precision.

   void vDSP_measqv (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input vector. If passed an array of length 0, this function returns a NaN.

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the mean value of the squares of the elements of vector A and stores this value in scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_measqvD

Vector mean square value; double precision.

   void vDSP_measqvD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the mean value of the squares of the elements of vector A and stores this value in scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_minmgv

Vector minimum magnitude; single precision.

   void vDSP_minmgv (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input vector. If passed an array of length 0, this function returns +INF.

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the element with the least magnitude in vector A and copies this value to scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_minmgvD

Vector minimum magnitude; double precision.

   void vDSP_minmgvD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the element with the least magnitude in vector A and copies this value to scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_minmgvi

Vector minimum magnitude with index; single precision.

   void vDSP_minmgvi (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length * IC,
   vDSP_Length N);

Parameters

A

Single-precision real input vector. If passed a zero vector, this function returns a value of +INF with an indeterminate index.

I

Stride for A

C

Output scalar

IC

Output scalar index

N

Count

Discussion

This performs the operation

Copies the element with the least magnitude from real vector A to real scalar C, and writes its zero-based index to integer scalar IC. The index is the actual array index, not the pre-stride index. If vector A contains more than one instance of the least magnitude, IC contains the index of the first instance.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_minmgviD

Vector minimum magnitude with index; double precision.

   void vDSP_minmgviD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length * IC,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Output scalar

IC

Output scalar

N

Count

Discussion

This performs the operation

Copies the element with the least magnitude from real vector A to real scalar C, and writes its zero-based index to integer scalar IC. The index is the actual array index, not the pre-stride index. If vector A contains more than one instance of the least magnitude, IC contains the index of the first instance.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_minv

Vector minimum value.

   void vDSP_minv (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input vector. If passed an array of length 0, this function returns +INF.

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the element with the least value in vector A and copies this value to scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_minvD

Vector minimum value; double precision.

   void vDSP_minvD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the element with the least value in vector A and copies this value to scalar C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_minvi

Vector minimum value with index; single precision.

   void vDSP_minvi (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length * IC,
   vDSP_Length N);

Parameters

A

Single-precision real input vector. If passed a zero vector, this function returns a value of +INF with an indeterminate index.

I

Stride for A

C

Output scalar

IC

Output scalar index

N

Count

Discussion

This performs the operation

Copies the element with the least value from real vector A to real scalar C, and writes its zero-based index to integer scalar IC. The index is the actual array index, not the pre-stride index. If vector A contains more than one instance of the least value, IC contains the index of the first instance.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_minviD

Vector minimum value with index; double precision.

   void vDSP_minviD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length * IC,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Output scalar

IC

Output scalar

N

Count

Discussion

This performs the operation

Copies the element with the least value from real vector A to real scalar C, and writes its zero-based index to integer scalar IC. The index is the actual array index, not the pre-stride index. If vector A contains more than one instance of the least value, IC contains the index of the first instance.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_mvessq

Vector mean of signed squares; single precision.

   void vDSP_mvessq (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input vector.

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the mean value of the signed squares of the elements of vector A and stores this value in *C. If A is an array of length 0, this function returns a NaN. .

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_mvessqD

Vector mean of signed squares; double precision.

   void vDSP_mvessqD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Output scalar

N

Count

Discussion

This performs the operation

Finds the mean value of the signed squares of the elements of vector A and stores this value in *C. If A is an array of length 0, this function returns a NaN.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_rmsqv

Vector root-mean-square; single precision.

   void vDSP_rmsqv (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input vector. If passed an array of length 0, this function returns a NaN.

I

Stride for A

C

Single-precision real output scalar

N

Count

Discussion

This performs the operation

Calculates the root mean square of the elements of A and stores the result in *C

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_rmsqvD

Vector root-mean-square; double precision.

   void vDSP_rmsqvD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Double-precision real output scalar

N

Count

Discussion

This performs the operation

Calculates the root mean square of the elements of A and stores the result in *C

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_sve

Vector sum; single precision.

   void vDSP_sve (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input vector.

I

Stride for A

C

Single-precision real output scalar

N

Count

Discussion

This performs the operation

Writes the sum of the elements of A into *C. If A is a vector with zero elements, this function returns 0 in *C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_sveD

Vector sum; double precision.

   void vDSP_sveD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input vector

I

Stride for A

C

Double-precision real output scalar

N

Count

Discussion

This performs the operation

Writes the sum of the elements of A into *C. If A is a vector with zero elements, this function returns 0 in *C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_svemg

Vector sum of magnitudes; single precision.

   void vDSP_svemg (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input scalar. If passed an value of 0, this function returns 0.

I

Stride for A

C

Single-precision real output scalar

N

Count

Discussion

This performs the operation

Writes the sum of the magnitudes of the elements of A into C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_svemgD

Vector sum of magnitudes; double precision.

   void vDSP_svemgD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input scalar

I

Stride for A

C

Double-precision real output scalar

N

Count

Discussion

This performs the operation

Writes the sum of the magnitudes of the elements of A into C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_svesq

Vector sum of squares; single precision.

   void vDSP_svesq (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input scalar. If passed an value of 0, this function returns 0.

I

Stride for A

C

Single-precision real output scalar

N

Count

Discussion

This performs the operation

Writes the sum of the squares of the elements of A into C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_svesqD

Vector sum of squares; double precision.

   void vDSP_svesqD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input scalar

I

Stride for A

C

Double-precision real output scalar

N

Count

Discussion

This performs the operation

Writes the sum of the squares of the elements of A into C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_svs

Vector sum of signed squares; single precision.

   void vDSP_svs (float * A,
   vDSP_Stride I,
   float * C,
   vDSP_Length N);

Parameters

A

Single-precision real input scalar. If passed an value of 0, this function returns 0.

I

Stride for A

C

Single-precision real output scalar

N

Count

Discussion

This performs the operation

Writes the sum of the signed squares of the elements of A into C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_svsD

Vector sum of signed squares; double precision.

   void vDSP_svsD (double * A,
   vDSP_Stride I,
   double * C,
   vDSP_Length N);

Parameters

A

Double-precision real input scalar

I

Stride for A

C

Double-precision real output scalar

N

Count

Discussion

This performs the operation

Writes the sum of the signed squares of the elements of A into C.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_zdotpr

Calculates the complex dot product of complex vectors signal1 and signal2 and leaves the result in complex vector result; single precision.

   void vDSP_zdotpr (DSPSplitComplex * A,
   vDSP_Stride I,
   DSPSplitComplex * B,
   vDSP_Stride J,
   DSPSplitComplex * C,
   vDSP_Length N);

Discussion

This performs the operation

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_zdotprD

Calculates the complex dot product of complex vectors signal1 and signal2 and leaves the result in complex vector result; double precision.

   void vDSP_zdotprD (DSPDoubleSplitComplex * A,
   vDSP_Stride I,
   DSPDoubleSplitComplex * B,
   vDSP_Stride J,
   DSPDoubleSplitComplex * C,
   vDSP_Length N);

Discussion

This performs the operation

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_zidotpr

Calculates the conjugate dot product (or inner dot product) of complex vectors signal1 and signal2 and leave the result in complex vector result; single precision.

   void vDSP_zidotpr (DSPSplitComplex * A,
   vDSP_Stride I,
   DSPSplitComplex * B,
   vDSP_Stride J,
   DSPSplitComplex * C,
   vDSP_Length N);

Discussion

This performs the operation

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_zidotprD

Calculates the conjugate dot product (or inner dot product) of complex vectors signal1 and signal2 and leave the result in complex vector result; double precision.

   void vDSP_zidotprD (DSPDoubleSplitComplex * A,
   vDSP_Stride I,
   DSPDoubleSplitComplex * B,
   vDSP_Stride J,
   DSPDoubleSplitComplex * C,
   vDSP_Length N);

Discussion

This performs the operation

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_zrdotpr

Calculates the complex dot product of complex vector A and real vector B and leaves the result in complex vector C; single precision.

   void vDSP_zrdotpr (DSPSplitComplex * A,
   vDSP_Stride I,
   const float B[],
   vDSP_Stride J,
   DSPSplitComplex * C,
   vDSP_Length N);

Discussion

This performs the operation

Availability

• Available in Mac OS X v10.4 and later.

Declared In

vDSP_zrdotprD

Calculates the complex dot product of complex vector A and real vector B and leaves the result in complex vector C; double precision.

   void vDSP_zrdotprD (DSPDoubleSplitComplex * A,
   vDSP_Stride I,
   const double B[],
   vDSP_Stride J,
   DSPDoubleSplitComplex * C,
   vDSP_Length N);

Discussion

This performs the operation

Availability

• Available in Mac OS X v10.4 and later.

Declared In

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