MATLAB Emulation Functions

Description

Wrapper functions and variables used to replicate MATLAB function calls as best possible to simplify porting.

Details

They are no more complete than absolutely necessary and are quite possibly broken for fringe cases.

For a complete list of functions, use library(help="matlab").
For a high-level summary of the changes for each revision, use file.show(system.file("NEWS", package="matlab")).

Note

In certain cases, these may not correspond exactly with MATLAB API as sometimes it just wasn't possible.

Author(s)

P. Roebuck proebuck1701@gmail.com

MATLAB ceil function

Description

Rounds to the nearest integer.

Usage

ceil(x)

Arguments

Details

Simply invokes ceiling for those more used to C library API name.

Value

Returns numeric vector containing smallest integers not less than the corresponding elements of argument x.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

fix, Round

Examples

ceil(c(0.9, 1.3, 2.4))

MATLAB cell function

Description

Create cell array.

Usage

cell(...)

Arguments

Value

Returns list consisting of empty matrices. Defaults to square if dimension argument resolves to a single value.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

ones, zeros

Examples

cell(3)
cell(c(3, 3))			# same thing
cell(3, 3)			# same thing
cell(size(matrix(NA, 3, 3)))	# same thing

MATLAB colorbar function

Description

Displays colorbar showing the color scale.

Usage

colorbar(C, location=c("EastOutside", "WestOutside", "NorthOutside", "SouthOutside"), ...)

Arguments

Details

The values of the elements of C are indices into the current palette that determine the color of each patch.

This implementation differs a bit from its MATLAB counterpart in that the values must be passed explicitly.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

imagesc, jet.colors, layout, par

Examples

doPlot <- function(C,
                   cb.loc=c("EastOutside",
                            "WestOutside",
                            "NorthOutside",
                            "SouthOutside"),
                   ...) {
    saved.par <- par(no.readonly=TRUE)
    on.exit(par(saved.par))

    layout.EO <- function() {
        ## divide the device into one row and nine columns
        ## allocate figure 1 the first eight columns
        ## allocate figure 2 the last column
        layout(matrix(c(1, 1, 1, 1, 1, 1, 1, 1, 2), ncol=9))
    }

    layout.WO <- function() {
        ## divide the device into one row and nine columns
        ## allocate figure 1 the last eight columns
        ## allocate figure 2 the first column
        layout(matrix(c(2, 1, 1, 1, 1, 1, 1, 1, 1), ncol=9))
    }

    layout.NO <- function() {
        ## divide the device into six rows and one column
        ## allocate figure 1 the last five rows
        ## allocate figure 2 the first row
        layout(matrix(c(2, 1, 1, 1, 1, 1), nrow=6))
    }

    layout.SO <- function() {
        ## divide the device into six rows and one column
        ## allocate figure 1 the first five rows
        ## allocate figure 2 the last row
        layout(matrix(c(1, 1, 1, 1, 1, 2), nrow=6))
    }

    location <- match.arg(cb.loc)
    switch(EXPR=location,
           EastOutside  = layout.EO(),
           WestOutside  = layout.WO(),
           NorthOutside = layout.NO(),
           SouthOutside = layout.SO())

    imagesc(C, ...)
    colorbar(C, location, ...)
}

values <- matrix(c(seq(1,  5, by=1),
                   seq(2, 10, by=2),
                   seq(3, 15, by=3)), nrow=3, byrow=TRUE)

dev.new(width=8, height=7)
doPlot(values, "EastOutside", col=jet.colors(16))

MATLAB eye function

Description

Create an identity matrix.

Usage

eye(m, n)

Arguments

Value

Returns matrix of order 1. Defaults to square if second dimension argument n not provided.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

ones, zeros

Examples

eye(3)

MATLAB factor function

Description

Performs prime factorization.

Usage

factors(n)

Arguments

Details

Computes the prime factors of n in ascending order, each one as often as its multiplicity requires, such that n == prod(factors(n)).

Value

Returns vector containing the prime factors of n.

Note

The corresponding MATLAB function is called 'factor', but was renamed here to avoid conflict with R's compound object class.

Author(s)

H. Borchers hwborchers@googlemail.com, P. Roebuck proebuck1701@gmail.com

See Also

isprime, primes

Examples

factors(1002001)       # 7  7  11  11  13  13
factors(65537)         # is prime
## Euler's calculation
factors(2^32 + 1)      # 641  6700417

MATLAB fileparts function

Description

Return filename parts.

Usage

fileparts(pathname)

Arguments

Details

Determines the path, filename, extension, and version for the specified file. The returned ext contains a dot (.) before the file extension. The returned versn is always an empty string as the field is provided for compatibility with its namesake's results.

Value

Returns a list with components:

Note

Returns same insane results as does its namesake when handling relative directories, UNIX hidden files, and tilde expansion. Hidden files are returned with name containing a zero length vector and ext containing the actual name. For best results, use this routine to process files, not directories.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

fullfile

Examples

## Rename dot-txt file as dot-csv
ans <- fileparts("/home/luser/foo.txt")
fullfile(ans$pathstr, paste(ans$name, "csv", sep="."))   # /home/luser/foo.csv

MATLAB filesep function

Description

Returns the character that separates directory names in filenames.

Usage

filesep

Details

Variable that contains the value of .Platform$file.sep.

Value

Returns character representing this platform's file separator.

Note

Implemented as an R variable rather than a function such that it more closely resembles normal MATLAB usage.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

fileparts, fullfile, pathsep

MATLAB find function

Description

Finds indices of elements.

Usage

find(x)

Arguments

Details

If expression is not logical, finds indices of nonzero elements of argument x.

Value

Returns indices of corresponding elements matching the expression x.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

find(-3:3 >= 0)
find(c(0, 1, 0, 2, 3))

MATLAB fix function

Description

Rounds toward zero.

Usage

fix(A)

Arguments

Details

Simply invokes trunc.

Value

Returns vector containing integers by truncating the corresponding values of argument A toward zero.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

ceil, Round

Examples

fix(c(1.3, 2.5, 3.7))

MATLAB matrix flip functions

Description

Flips matrices either left-right or up-down.

Usage

fliplr(object)
flipud(object)

Arguments

Details

These are S4 generic functions.

Value

Return value is the same type as argument object.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

rot90

Examples

fliplr(1:9)
flipud(1:9)	# same as previous since vectors have no orientation in R
fliplr(matrix(1:9, 3, 3, byrow=TRUE))
flipud(matrix(1:9, 3, 3, byrow=TRUE))

MATLAB fullfile function

Description

Contructs path to a file from components in platform-independent manner

Usage

fullfile(...)

Arguments

Details

Builds a full filename from the directories and filename specified. This is conceptually equivalent to

    paste(dir1, dir2, dir3, filename, sep=filesep)

  

with care taken to handle cases when directories begin or end with a separator.

Value

Returns character vector of arguments concatenated term-by-term and separated by file separator if all arguments have a positive length; otherwise, an empty character vector.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

fileparts, filesep

Examples

fullfile("", "etc", "profile")	# /etc/profile

MATLAB hilb function

Description

Create a Hilbert matrix.

Usage

hilb(n)

Arguments

Details

The Hilbert matrix is a notable example of a poorly conditioned matrix. Its elements are

    H[i, j] = 1 / (i + j - 1)

.

Value

Returns an n-by-n matrix constructed as described above.

Author(s)

H. Borchers hwborchers@googlemail.com, P. Roebuck proebuck1701@gmail.com

Examples

hilb(3)

MATLAB imagesc function

Description

Scales image data to the full range of the current palette and displays the image.

Usage

imagesc(x=seq(ncol(C)), y=seq(nrow(C)), C, col=jet.colors(12), ...)

Arguments

Details

Each element of C corresponds to a rectangular area in the image. The values of the elements of C are indices into the current palette that determine the color of each patch.

The method interprets the matrix data as a table of f(x[i], y[j]) values, so that the x axis corresponds to column number and the y axis to row number, with row 1 at the top, i.e., the same as the conventional printed layout of a matrix.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

image, jet.colors, par

Examples

values <- matrix(c(seq(1,  5, by=1),
                   seq(2, 10, by=2),
                   seq(3, 15, by=3)), nrow=3, byrow=TRUE)
imagesc(values, xlab="cols", ylab="rows", col=jet.colors(16))

MATLAB isempty function

Description

Determine if object is empty.

Usage

isempty(A)

Arguments

Details

An empty object has at least one dimension of size zero.

Value

Returns TRUE if x is an empty object; otherwise, FALSE.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

isempty(1:3)  # FALSE
isempty(array(NA, c(2, 0, 2)))	# TRUE

MATLAB isprime function

Description

Array elements that are prime numbers.

Usage

isprime(x)

Arguments

Value

Returns an array (or vector) the same size as x containing logical 1 (true) for the elements of x which are prime, and logical 0 (false) otherwise.

Author(s)

H. Borchers hwborchers@googlemail.com, P. Roebuck proebuck1701@gmail.com

See Also

factors, primes

Examples

x <- c(2, 3, 0, 6, 10)
ans  <- isprime(x)	## 1, 1, 0, 0, 0
as.logical(ans)         ## true, true, false, false, false

MATLAB jet function

Description

Creates a vector of n colors beginning with dark blue, ranging through shades of blue, cyan, green, yellow and red, and ending with dark red.

Usage

jet.colors(n)

Arguments

Value

Returns vector of n color names. This can be used either to create a user-defined color palette for subsequent graphics, a col= specification in graphics functions, or in par.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

palette, par, rgb

Examples

require(graphics)
x <- 1:16
pie(x, col=jet.colors(length(x)))

MATLAB linspace function

Description

Generate linearly spaced vectors.

Usage

linspace(a, b, n=100)

Arguments

Details

Similar to colon operator but gives direct control over the number of points. Note also that although MATLAB doesn't specifically document this, the number of points generated is actually floor(n).

Value

Returns vector containing containing n points linearly spaced between a and b inclusive. If \code{n} < 2, the result will be the ending point b.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

logspace

Examples

linspace(1, 10, 4)

MATLAB logspace function

Description

Generate logarithmically spaced vectors.

Usage

logspace(a, b, n=50)

Arguments

Details

Useful for creating frequency vectors, it is a logarithmic equivalent of linspace.

Value

Returns vector containing containing n points logarithmically spaced between decades 10^\code{a} and 10^\code{b}. For n < 2, b is returned.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

linspace

Examples

logspace(1, pi, 36)

MATLAB magic function

Description

Create a magic square.

Usage

magic(n)

Arguments

Details

The value of the characteristic sum for a magic square of order n is sum(1:n^2)/n. The order n must be a scalar greater than or equal to 3; otherwise, the result will be either a nonmagic square, or else the degenerate magic squares 1 and [].

Value

Returns an n-by-n matrix constructed from the integers 1 through N^2 with equal row and column sums.

Note

A magic square, scaled by its magic sum, is doubly stochastic.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

ones, zeros

Examples

magic(3)

MATLAB meshgrid functions

Description

Generate X and Y matrices for three-dimensional plots.

Usage

meshgrid(x, y, z, nargout=2)

Arguments

Details

In the first example below, the domain specified by vectors x and y are transformed into two arrays which can be used to evaluate functions of two variables and three-dimensional surface plots. The rows of the output array x are copies of the vector x; columns of the output array y are copies of the vector y.

The second example below is syntactic sugar for specifying meshgrid(x, x).

The third example below produces three-dimensional arrays used to evaluate functions of three variables and three-dimensional volumetric plots.

Value

Returns list containing eiher two or three matrices depending on the value of nargout.

Note

Limited to two- or three-dimensional Cartesian space.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

meshgrid(1:3, 10:14)            # example 1
meshgrid(1:3)                   # example 2
meshgrid(5:8, 10:14, 2:3, 3)    # example 3

MATLAB mod/rem functions

Description

Provides modulus and remainder after division.

Usage

mod(x, y)
rem(x, y)

Arguments

Value

Returns vector containing result of the element by element operations.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

## same results with x, y having the same sign
mod(5, 3)
rem(5, 3)
## same results with x, y having different signs
mod(-5, 3)
rem(-5, 3)

MATLAB multiline plot colors

Description

Creates a vector of colors equivalent to MATLAB's default colors to use for multiline plots.

Usage

multiline.plot.colors()

Details

This is equivalent to the MATLAB command

    get(gca, 'ColorOrder')

  

Value

Returns vector of color names. This can be used either to create a user-defined color palette for subsequent graphics, a col= specification in graphics functions, or in par.

Note

Method should be considered experimental and will most likely be removed and replaced with similar functionality in the near future.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

palette, par, rgb

Examples

require(graphics)
x <- matrix(1:16, nrow=2, byrow=TRUE)
matplot(x, type="l", col=multiline.plot.colors())

MATLAB ndims function

Description

Provides number of array dimensions.

Usage

ndims(A)

Arguments

Details

Simply invokes length(size(A)).

Value

Returns the number of dimensions in the array A.

Note

The number of dimensions is always greater than or equal to 2. Initial implementation returned length.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

size

Examples

ndims(2:9)			# 2
ndims(magic(4))			# 2
ndims(array(1:8, c(2,2,2)))	# 3

MATLAB nextpow2 function

Description

Smallest power of 2 greater than or equal to its argument.

Usage

nextpow2(x)

Arguments

Details

Computes the smallest power of two that is greater than or equal to the absolute value of x. (That is, p that satisfies 2^p \ge abs(x)). For negative or complex values, the absolute value will be taken.

Value

Returns numeric result containing integer p as described above. Nonscalar input returns an element-by-element result (of same size/dimensions as its input).

Author(s)

H. Borchers hwborchers@googlemail.com, P. Roebuck proebuck1701@gmail.com

See Also

pow2

Examples

nextpow2(10)                   # 4
nextpow2(1:10)                 # 0 1 2 2 3 3 3 3 4 4
nextpow2(-2^10)                # 10
nextpow2(.Machine$double.eps)  # -52
nextpow2(c(0.5, 0.25, 0.125))  # -1 -2 -3

MATLAB numel function

Description

Provides number of elements in array A or subscripted array expression.

Usage

numel(A, varargin)

Arguments

Value

Returns prod(size(A)).

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

prod, size

Examples

numel(2:9)	# 8
numel(magic(4))	# 16

MATLAB ones/zeros functions

Description

Create a matrix consisting of all ones or zeros.

Usage

ones(...)
zeros(...)

Arguments

Value

Returns matrix consisting only of ones (or zeros). Defaults to square if dimension argument resolves to a single value.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

eye

Examples

ones(3)
ones(c(3, 3))                   # same thing 
ones(3, 3)                      # same thing
ones(size(matrix(NA, 3, 3)))    # same thing
zeros(3)

MATLAB padarray function

Description

Pad array.

Usage

padarray(A, padsize, padval=0, direction=c("both", "pre", "post"))

Arguments

Details

This is an S4 generic function.

Value

Return value is the same type as argument A with requested padding.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

padarray(1:4, c(0, 2))				# 0 0 [1 2 3 4] 0 0
padarray(1:4, c(0, 2), -1)			# -1 -1 [1 2 3 4] -1 -1
padarray(1:4, c(0, 2), -1, "post")		# [1 2 3 4] -1 -1
padarray(1:4, c(0, 3), "symmetric", "pre")	# 3 2 1 [1 2 3 4]
padarray(letters[1:5], c(0, 3), "replicate")	# a a a [a b c d e] e e e
padarray(letters[1:5], c(0, 3), "circular", "post")	# [a b c d e] a b c

MATLAB pascal function

Description

Generate Pascal matrix.

Usage

pascal(n, k=0)

Arguments

Details

Specifying k=0 returns symmetric positive definite matrix with integer entries taken from Pascal's triangle.

Specifying k=1 returns the lower triangular Cholesky factor (up to the signs of the columns) of the Pascal matrix.

Specifying k=2 returns a cube root of the identity matrix.

Value

Returns matrix of order n according to specified option k.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

pascal(4)
pascal(3, 2)

MATLAB pathsep function

Description

Returns the character that separates directory names in a list such as the PATH environment variable.

Usage

pathsep

Details

Variable that contains the value of .Platform$path.sep.

Value

Returns character representing this platform's path separator.

Note

Implemented as an R variable rather than a function such that it more closely resembles normal MATLAB usage.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

filesep

MATLAB pow2 function

Description

Power with base 2.

Usage

pow2(f, e)

Arguments

Details

Computes the expression f * 2^e for corresponding elements of f and e. If e is missing, it sets e to f and f to 1. Imaginary parts of complex values are ignored unless e is missing.

Value

Returns numeric vector constructed as described above.

Author(s)

H. Borchers hwborchers@googlemail.com, P. Roebuck proebuck1701@gmail.com

See Also

nextpow2

Examples

pow2(c(0, 1, 2, 3))               # 1 2 4 8
pow2(c(0, -1, 2, 3), c(0,1,-2,3)) # 0.0 -2.0  0.5 24.0
pow2(1i)                          # 0.7692389+0.6389613i

# For IEEE arithmetic...
pow2(1/2, 1)                      # 1
pow2(pi/4, 2)                     # pi
pow2(-3/4, 2)                     # -3
pow2(1/2, -51)                    # .Machine$double.eps
pow2(1/2, -1021)                  # .Machine$double.xmin

MATLAB primes function

Description

Generate a list of prime numbers.

Usage

primes(n)

Arguments

Details

Generates the list of prime numbers less than or equal to n using a variant of the basic "Sieve of Eratosthenes" algorithm. This approach is reasonably fast, but requires a copious amount of memory when n is large. A prime number is one that has no other factors other than 1 and itself.

Value

Returns numeric vector containing prime numbers less than or equal to argument n.

Author(s)

H. Borchers hwborchers@googlemail.com, P. Roebuck proebuck1701@gmail.com

See Also

isprime, factors

Examples

primes(1000)
length(primes(1e6))    #   78498 prime numbers less than one million
## Not run: 
  length(primes(1e7))  #  664579 prime numbers less than ten million
  length(primes(1e8))  # 5761455 prime numbers less than one hundred million

## End(Not run)

MATLAB repmat function

Description

Replicate and tile a matrix.

Usage

repmat(A, ...)

Arguments

Value

Returns matrix with value A tiled to the number of dimensions specified. Defaults to square if dimension argument resolves to a single value.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

ones, zeros

Examples

repmat(1, 3)                       # same as ones(3)
repmat(1, c(3, 3))                 # same thing 
repmat(1, 3, 3)                    # same thing
repmat(1, size(matrix(NA, 3, 3)))  # same thing
repmat(matrix(1:4, 2, 2), 3)

MATLAB reshape function

Description

Reshape matrix or array.

Usage

reshape(A, ...)

Arguments

Details

In the first example below, an m-by-n matrix is created whose elements are taken column-wise from A. An error occurs if A does not have m*n elements.

In the second example below, an n-dimensional array with the same elements as A but reshaped to have the size m-by-n-by-p. The product of the specified dimensions must be the same as prod(size(A)).

In the third example below, an n-dimensional array with the same elements as A but reshaped to siz, a vector representing the dimensions of the reshaped array. The quantity prod(siz) must be the same as prod(size(A)).

Value

Returns matrix (or array) of requested dimensions containing the elements of A.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

Xmat.2d <- matrix(1:12, nrow=4, ncol=3)
reshape(Xmat.2d, 6, 2)                   # example 1
reshape(Xmat.2d, c(6, 2))                    # same thing
Xarr.3d <- reshape(Xmat.2d, c(6, 2, 1))  # example 2
reshape(Xmat.2d, size(Xarr.3d))          # example 3

MATLAB rosser function

Description

Create the Rosser matrix, a classic symmetric eigenvalue test problem.

Usage

rosser()

Details

The returned matrix has the following features:

• a double eigenvalue

• three nearly equal eigenvalues

• dominant eigenvalues of opposite sign

• a zero eigenvalue

• a small, nonzero eigenvalue

Value

Returns an 8-by-8 matrix with integer elements.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

rosser()

MATLAB rot90 function

Description

Rotates matrix counterclockwise k*90 degrees.

Usage

rot90(A, k=1)

Arguments

Details

Rotating 4 times (360 degrees) returns the original matrix unchanged.

Value

Returns matrix corresponding to argument A having been rotated argument k number of times.

Author(s)

P. Roebuck proebuck1701@gmail.com

See Also

fliplr, flipud

Examples

rot90(matrix(1:4, 2, 2))

MATLAB size function

Description

Provides dimensions of X.

Usage

size(X, dimen)

Arguments

Details

This is an S4 generic function. Vector will be treated as a single row matrix. Stored value is equivalent to dim.

Value

Returns object of class size_t containing the dimensions of input argument X if invoked with a single argument. Returns integer value of specified dimension if invoked with two arguments. If dimen specifies a higher dimension than exists, returns 1 representing the singleton dimension.

Note

Handling of vectors is different than in initial implementation. Initial implementation returned length.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

size(2:9)			# 1 8
size(matrix(1:8, 2, 4))		# 2 4
size(matrix(1:8, 2, 4), 2)	# 4
size(matrix(1:8, 2, 4), 3)	# 1

Class "size_t"

Description

This class represents the dimensions of another R object

Objects from the Class

Objects can be created by calls of the form new("size_t", ...). Use of generator method is preferred.

Slots

.Data:

object of class "integer" containing size values

Extends

Class "integer", from data part. Class "vector", by class "integer". Class "numeric", by class "integer".

Note

Internal class supporting size.

Author(s)

P. Roebuck proebuck1701@gmail.com

MATLAB std function

Description

Computes the standard deviation of the values of x.

Usage

std(x, flag=0)

Arguments

Details

Simply invokes sd.

Value

Return value depends on argument x. If vector, returns the standard deviation. If matrix, returns vector containing the standard deviation of each column.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

std(1:2) ^ 2

MATLAB strcmp function

Description

Compare strings.

Usage

strcmp(S, T)

Arguments

Details

Comparisons are case-sensitive and any leading and trailing blanks in either of the strings are explicitly included in the comparison.

Value

Returns TRUE if S is identical to T; otherwise, FALSE.

Note

Value returned is the opposite of the C language convention.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

strcmp("foo", "bar")  # FALSE
strcmp(c("yes", "no"), c("yes", "no"))	# TRUE

MATLAB sum function

Description

Provides sum of elements.

Usage

sum(x, na.rm=FALSE)

Arguments

Details

This is an S4 generic function.

Value

Return value depends on argument x. If vector, returns the same as sum. If matrix, returns vector containing the sum of each column.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

sum(1:9)
sum(matrix(1:9, 3, 3))

MATLAB timer functions

Description

Provides stopwatch timer. Function tic starts the timer and toc updates the elapsed time since the timer was started.

Usage

tic(gcFirst=FALSE)
toc(echo=TRUE)

Arguments

Details

Provides analog to system.time. Function toc can be invoked multiple times in a row.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

tic()
for(i in 1:100) mad(runif(1000))	# kill time
toc()

MATLAB vander function

Description

Generate Vandermonde matrix from a vector of numbers.

Usage

vander(v)

Arguments

Details

Generates the Vandermonde matrix whose columns are powers of the vector v (of length n) using the formula

    A[i, j] = v[i]^(n-j)

Used when fitting a polynomial to given points.

Value

Returns an n-by-n matrix constructed as described above.

Author(s)

H. Borchers hwborchers@googlemail.com, P. Roebuck proebuck1701@gmail.com

Examples

vander(1:5)