Add better sample for plots.jl

examples/FIR_design_plots.jl

@@ -1,80 +0,0 @@
-#' % FIR filter design with Julia
-#' % Matti Pastell
-#' % 21th April 2016
-
-#' # Introduction
-
-#' This an example of a julia script that can be published using
-#' [Weave](http://mpastell.github.io/Weave.jl/latest/usage/).
-#' The script can be executed normally using Julia
-#' or published to HTML or pdf with Weave.
-#' Text is written in markdown in lines starting with "`#'` " and code
-#' is executed and results are included in the published document.
-
-#' Notice that you don't need to define chunk options, but you can using
-#' `#+`. just before code e.g. `#+ term=True, caption='Fancy plots.'`.
-#' If you're viewing the published version have a look at the
-#' [source](FIR_design_plots.jl) to see the markup.
-
-
-#' # FIR Filter Design
-
-#' We'll implement lowpass, highpass and ' bandpass FIR filters. If
-#' you want to read more about DSP I highly recommend [The Scientist
-#' and Engineer's Guide to Digital Signal
-#' Processing](http://www.dspguide.com/) which is freely available
-#' online.
-
-#' ## Calculating frequency response
-
-#' DSP.jl package doesn't (yet) have a method to calculate the
-#' the frequency response of a FIR filter so we define it:
-
-using Plots, DSP
-plotlyjs()
-
-function FIRfreqz(b::Array, w = linspace(0, π, 1024))
-    n = length(w)
-    h = Array{Complex64}(n)
-    sw = 0
-    for i = 1:n
-      for j = 1:length(b)
-        sw += b[j]*exp(-im*w[i])^-j
-      end
-      h[i] = sw
-      sw = 0
-    end
-    return h
-end
-
-
-#' ## Design Lowpass FIR filter
-
-#' Designing a lowpass FIR filter is very simple to do with DSP.jl, all you
-#' need to do is to define the window length, cut off frequency and the
-#' window. We will define a lowpass filter with cut off frequency at 5Hz for a signal
-#' sampled at 20 Hz.
-#' We will use the Hamming window, which is defined as:
-#' $w(n) = \alpha - \beta\cos\frac{2\pi n}{N-1}$, where $\alpha=0.54$ and $\beta=0.46$
-
-
-fs = 20
-f = digitalfilter(Lowpass(5, fs = fs), FIRWindow(hamming(61)))
-w = linspace(0, pi, 1024)
-h = FIRfreqz(f, w)
-
-#' ## Plot the frequency and impulse response
-
-#' The next code chunk is executed in term mode, see the [script](FIR_design.jl) for syntax.
-#+ term=true
-
-h_db = log10(abs(h))
-ws = w/pi*(fs/2)
-plot(y = h_db, x = ws,
-      xlabel = "Frequency (Hz)", ylabel = "Magnitude (db)")
-
-#' And again with default options
-
-h_phase = unwrap(-atan2(imag(h),real(h)))
-plot(y = h_phase, x = ws,
-    xlabel = "Frequency (Hz)", ylabel = "Phase (radians)")

examples/plots_example.mdw

@@ -0,0 +1,14 @@
+
+<<>>=
+using Plots
+pyplot()
+x = linspace(0, 2π, 2056)
+@
+
+<<>>=
+plot(sinc(x))
+@
+
+<<>>=
+plot(-sinc(x))
+@