# blockfrfreal

Real component of a Frequency Response Function (FRF) calculated using blocking.

## Syntax

blockfrfreal(vec_expr1, vec_expr_2, block_size, overlap)

## Argument

vec_expr1
The input to a system.
vec_expr2
The output from a given system.
block_size
The number of elements to be used for each FRF (should be a power of 2).
overlap
The number of elements shared between consecutive blocks.

## Example

Templex Expression Result
{blockfrfreal(c1.y, c2.y, 256, 128)} A vector is generated which is the real component in the frequency domain of the FRF of input c1.y and output c2.y, using a block size of 256 and an overlap 128.
Curve Math Vectors Result
x = freq(c1.x[0:255:1])

y = blockfrfreal(c1.y, c2.y, 256, 128)

Given c1 and c2, a curve is created which is the real component in the frequency domain of the FRF of input c1 and output c2, using a block size of 256 and an overlap 128.

## Comments

The blockfrfreal function uses blocking to calculate the real component of a Frequency Response Function (FRF). vec_expr_1 and vec_expr_2 are assumed to be evenly sampled. The resultant vector has a number of elements equal to the least power of two greater than or equal to block_size.

The FRF is complex-valued and used to map time-domain data into the frequency domain.

The blockfrfreal function is different from a normal FRF in that it introduces blocking. The input vector is subdivided into blocks, each having block_size number of elements. An FRF is then performed on each individual block. The results of these FRFs are then averaged to give the final result.