From fd1f13eb33215396e4ebcbdaaf4c068831264655 Mon Sep 17 00:00:00 2001
From: Matti Pastell <matti.pastell@helsinki.fi>
Date: Sun, 30 Oct 2016 18:50:02 +0200
Subject: [PATCH] Update examples for Julia 0.5, #54

---
 examples/FIR_design_plots.jl | 80 ++++++++++++++++++++++++++++++++++++
 examples/julia_sample.mdw    |  2 +-
 2 files changed, 81 insertions(+), 1 deletion(-)
 create mode 100644 examples/FIR_design_plots.jl

diff --git a/examples/FIR_design_plots.jl b/examples/FIR_design_plots.jl
new file mode 100644
index 0000000..6bfa39b
--- /dev/null
+++ b/examples/FIR_design_plots.jl
@@ -0,0 +1,80 @@
+#' % 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)")
diff --git a/examples/julia_sample.mdw b/examples/julia_sample.mdw
index dbee48d..4ac2163 100644
--- a/examples/julia_sample.mdw
+++ b/examples/julia_sample.mdw
@@ -17,7 +17,7 @@ weave("examples/julia_sample.mdw")
 
 <<term=true>>=
 x = 1:10
-d = {"Weave" => "testing"}
+d = Dict("Weave" => "testing")
 y = [2, 4 ,8]
 @