vprod

Functions

int main(int argc, char *argv[])

vprod [ option ] [ infile ]

• -l int

  • length of vector $(1\le L)$

• -m int

  • order of vector $(0\le L-1)$

• -t int

  • output interval $(1\le T)$

• -c

  • cumulative mode

• infile str

  • double-type vectors

• stdout

  • double-type product

The input of this command is

$$\begin{array}{ccc}\underset{L}{\underbrace{x_1(1),\dots ,x_1(L)}},& \underset{L}{\underbrace{x_2(1),\dots ,x_2(L)}},& \dots ,\end{array}$$

and the output is

$$\begin{array}{ccc}\underset{L}{\underbrace{p_0(1),\dots ,p_0(L)}},& \underset{L}{\underbrace{p_T(1),\dots ,p_T(L)}},& \dots ,\end{array}$$

where

$$p_t(l)=\prod _{\tau =1}^T{x}_{t+\tau }(l).$$

If $T$ is not given, the product of the whole input is computed.

echo 1 2 3 4 5 | x2x +ad | vprod | x2x +da
# 120

echo 2 3 4 5 | x2x +ad | vprod -c -t 1 | x2x +da
# 2
# 6
# 24
# 120

Parameters:

• argc – [in] Number of arguments.

• argv – [in] Argument vector.

Returns:

0 on success, 1 on failure.

See also

vsum vstat

class ProductAccumulation

Accumulate product of input vectors.

The input of is an $M$-th order vector:

$$\begin{array}{cccc}{x}_t(0),& x_t(1),& \dots ,& x_t(M).\end{array}$$

After running Run $T$ times, the following statistics are obtained:

$$\begin{array}{r}\begin{array}{rcl}{P}_0& =& T,\\ P_1(m)& =& \prod _{t=0}^{T-1}{x}_t(m).\end{array}\end{array}$$

Public Functions

explicit ProductAccumulation(int num_order, bool numerically_stable = false)

Parameters:

• num_order – [in] Order of vector, $M$.

• numerically_stable – [in] If true, use a numerically stable algorithm.

inline int GetNumOrder() const

Returns:

Order of vector.

inline bool IsValid() const

Returns:

True if this object is valid.

bool GetNumData(const ProductAccumulation::Buffer &buffer, int *num_data) const

Parameters:

• buffer – [in] Buffer.

• num_data – [out] Number of accumulated data.

Returns:

True on success, false on failure.

bool GetProduct(const ProductAccumulation::Buffer &buffer, std::vector<double> *product) const

Parameters:

• buffer – [in] Buffer.

• product – [out] Product of accumulated data.

Returns:

True on success, false on failure.

bool GetGeometricMean(const ProductAccumulation::Buffer &buffer, std::vector<double> *mean) const

Parameters:

• buffer – [in] Buffer.

• mean – [out] Geometric mean of accumulated data.

Returns:

True on success, false on failure.

void Clear(ProductAccumulation::Buffer *buffer) const

Clear buffer.

Parameters:

buffer – [inout] Buffer.

bool Run(const std::vector<double> &data, ProductAccumulation::Buffer *buffer) const

Accumulate product.

Parameters:

• data – [in] $M$-th order input vector.

• buffer – [inout] Buffer.

Returns:

True on success, false on failure.

class Buffer

Buffer for ProductAccumulation class.