added interpolation methods for integrals and derivatives - gsl-shell.git - gsl-shell

diff --git a/examples/interp.lua b/examples/interp.lua
index bfc976b2..f733ef63 100644
--- a/examples/interp.lua
+++ b/examples/interp.lua

@@ -1,13 +1,26 @@

function demo1()

+

+ local w = window('v..')

local N = 8

local xsmp = |k| 2*pi*(k-1)/N

- local x, y = new(N, 1, xsmp), new(N, 1, |k| sin(xsmp(k)))

+ local x, y = new(N+1, 1, xsmp), new(N+1, 1, |k| sin(xsmp(k)))

+

+ local function interp_plot(tp)

+ local p = plot(string.format('%s interpolation', tp))

+ p:add(xyline(x, y), 'black', {{'marker', size=5}})

+ local ap = interp(x, y, tp)

+ p:addline(fxline(|x| ap:eval(x), 0, 2*pi), 'blue', {{'dash', 7, 3, 3, 3}})

+ p:addline(fxline(|x| ap:deriv(x), 0, 2*pi))

+ p:add(fxline(cos, 0, 2*pi), 'blue', {{'stroke', width=0.75}, {'dash', 7,3}})

+ print(string.format('%s interp / integral between (%g, %g) = %g', tp,

+ 0, 2*pi, ap:integ(0, 2*pi)))

+ return p

+ end

+

+

local p = plot 'Akima Interpolation'

- p:show()

- p:addline(xyline(x, y))

- local ap = interp(x, y, 'akima')

- p:addline(fxline(|x| ap:eval(x), 0, 2*pi), 'blue', {{'dash', 7, 3, 3, 3}})

- return p, ap

+ w:attach(interp_plot('akima'), '1')

+ w:attach(interp_plot('cspline'), '2')

end

function demo2()

@@ -27,7 +40,10 @@ function demo2()

p:addline(xyline(x, y))

p:add(xyline(x, y), 'black', {{'marker', size= 5}})

local ap = interp(x, y, 'cspline')

- p:addline(fxline(|x| ap:eval(x), 0, x[N]), 'blue', {{'dash', 7, 3, 3, 3}})

+ local a, b = 0, x[N]

+ p:addline(fxline(|x| ap:eval(x), a, b), 'blue', {{'dash', 7, 3, 3, 3}})

+ p:addline(fxline(|x| ap:deriv(x), a, b), 'green')

+ print(string.format('Integral between (%g, %g) = %g', a, b, ap:integ(a, b)))

return p, ap

end