NewsΒΆ

May 2010

GSL Shell 0.10.0 released. It does includes many new features, bug fixes and a more extended set of GSL routines.

Among the most important things:

  • A contour plot algorithm is implemented. It is written entirely in Lua and it is quite fast. Its main limitations is that it is not able to treate discontinuous functions.
  • An “high precision” experimental contour plot is also available. It is much more computational expensive but it draws accurate smooths curve and it does require the derivatives of the function. As the algorithm is experimental it may fails in some cases. It will fails almost surely fails if the derivatives are discontinous or if both components becomes null at some point.
  • To print an expression now you don’t need to write an ‘=’ sign before
  • Some serious bugs related to the graphical window system have been fixed. Now the plotting system appears to be reliable in all situations both on Windows and X Window.
  • More GSL modules implemented:
    • Basis splines
    • Linear Regression
    • Eigensystems resolution
  • Many improvements in almost all the modules.
2 Janvier 2010

GSL Shell version 0.9.6 released.

A lot of exciting features have been introduced:

  • a new module for producing beautiful plots have been implemented. You can look at the many examples to see how does it works
    • in version 0.9.6 we have also introduced the support for alpha blending.
  • many special functions defined in the GSL library are now available from GSL shell.
  • the chapter with the examples have been updated with some examples to produce beautiful fractals curves.
16 October 2009

GSL Shell version alpha 0.6 released.

We have implemented a complete interface for the Fast Fourier Transform routines. You can now perform Fourier transform both of real or complex data very easily and GSL shell will select the appropriate algorithm and manage the required resources for you. The implemented interface does not introduce any significant overhead over the low-level GSL functions, data are never copied if not necessary and a smart interface has been disigned to allow uniform access to half-complex arrays.

A new notation has been introduced also for function literals. Now to express:

function(x, y)
  return 2*x+1
end

you can use the following syntax:

|x,y| 2*x+y

This allows to write very simple one-line definition. For example to define the complex matrix of Fourier transform you can write:

m = cnew(32, 32, |k,j| exp(2i*pi*(k-1)*(j-1)/32))

and you will obtain the following matrix:

m_{kj} = \exp(2i \pi k j/N) \; \textrm{with} \; N = 32

10 October 2009

GSL Shell version alpha 0.4 released. Now the interface for the Numerical Integration routines is complete. Now it is possible to easily integrate weighted functions like:

  • algebraic-logarithm singularities and the edges
  • Cauchy principal parts
  • oscillatory integrals

The integration of infinite interval is also supported including oscillatory integrand types, i.e. Fourier integrals.

Some examples of its usage:

fsin = function(x) return sin(x)/x end

-- simple integration of fsin between 0 and 24*pi
x, err = integ {f= fsin, points= {0, 24*pi}}

-- integral of exp(-x)/sqrt(x) between 0 and 5, should give
-- sqrt(pi)*erf(sqrt(5)), the demonstration is left as exercise
x, err = integ {f= function(x) return exp(-x) end, points= {0, 5},
                weight = {type='alglog', alpha = -0.5}}

-- the same of the first but uses a weight to trigger oscillatory method
x, err = integ {f= function(x) return 1/(x+1) end, points= {0, 24*pi},
                weight = {type='sin', omega = 1}}

-- a fourier integral
x, err = integ {f= function(x) exp(-x*x/2)*sin(5*x) end,
                points= {'inf', '+inf'},
                weight = {type='sin', omega = 4.5}}

-- a famous integral, should gives sqrt(2*pi)
x, err = integ {f= function(x) exp(-x*x/2) end, points= {'inf', '+inf'}}

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