How to go from a symbolic expression to a vector in MATLAB -

-

i working on function generate polynomial interpolants given set of ordered pairs. input indexes of node points in 1 vector, , values of function interpolated in second vector. generate symbolic expression lagrange polynomial interpolates set of points. able go symbolic form vector form comparison test functions , such. is, have generates polynomial p(x) in terms of symbolic variable x. sample polynomial vector, , values polynomial on (for example) linspace(-1,1,1000). if possible, how do it?

i guess i'll include code have far:

function l_poly = lpoly(x,f) %   returns polynomial interpolant computed lagrange's formula syms n=size(x,2); l_poly_vec = 1; l_poly=0; k=1:n,     l=1:n,         if (k ~= l)             l_poly_vec=l_poly_vec*(a-x(l))/(x(k)-x(l));         end     end     l_poly=l_poly+f(k)*l_poly_vec;     l_poly_vec = 1; end

i plan on adding third (or possibly fourth) input depending on how can solve issue. i'm guessing need length of vector want sample , endpoints.

if understand correctly, you've constructed lagrange interpolating polynomial using symbolic toolbox , wish evaluate on vector of values. 1 way use function sym2poly extract coefficients of symbolic polynomial, , use polyval evaluate it. alternatively, use matlabfunction convert symbolic expression regular matlab function; or use subs substitute in numeric value 'x'.

however, better off avoiding symbolic toolbox altogether , directly constructing coefficients of lagrange interpolating polynomial, or, better yet, use different interpolation scheme altogether. function interp1 might place start.


Comments

Post a Comment

Popular posts from this blog

python - Scipy curvefit RuntimeError:Optimal parameters not found: Number of calls to function has reached maxfev = 1000 -

-
Image
i want make logharitmic fit. keep getting runtime error: optimal parameters not found: number of calls function has reached maxfev = 1000 i use following script. can tell me go wrong? use spyder still beginner. import math import matplotlib mpl scipy.optimize import curve_fit import numpy np #data f1=[735.0,696.0,690.0,683.0,680.0,678.0,679.0,675.0,671.0,669.0,668.0,664.0,664.0] t1=[1,90000.0,178200.0,421200.0,505800.0,592200.0,768600.0,1036800.0,1371600.0,1630800.0,1715400.0,2345400.0,2409012.0] f1n=np.array(f1) t1n=np.array(t1) plt.plot(t1,f1,'ro',label="original data") # curvefit def func(t,a,b): return a+b*np.log(t) t=np.linspace(0,3600*24*28,13) popt, pcov = curve_fit(func, t, f1n, maxfev=1000) plt.plot(t, func(t, *popt), label="fitted curve") plt.legend(loc='upper left') plt.show() your original data t1 , f1 . therefore curve_fit should given t1 second argument, not t . popt, pcov = curve_fit(func,...
Read more

binding - How can you make the color of elements of a WPF DrawingImage dynamic? -

-
we have need make vector graphic images change color of elements within graphic @ runtime. seem setting colors based on either static or dynamic resource values wouldn't work. want have multiple versions of same graphic, each abilty set graphic elements (path, line, etc) different colors don't think dynamic resource approach work. leaves data binding seems right approach. update graphic use data binding expr instead of hard-coded brush color so: <drawingimage x:key="graphic1"> <drawingimage.drawing> <drawinggroup> <drawinggroup.children> <geometrydrawing geometry="f1 m 8.4073,23.9233l"> <geometrydrawing.pen> <pen linejoin="round" brush="{binding line1brush, mode=oneway}"/> </geometrydrawing.pen> </geometrydrawing> <geometrydrawing geometry="f1 m 3.6875,2.56251l"> <geometrydrawing....
Read more

c# - How to add a new treeview at the selected node? -

-
i have treeview 4 levels; parent, child, grandchild, great-grandchild. selectednode @ grandchild level. what i'm trying create new "treeview" @ grandchild - no, dont wnat create new node "selectednode" (grandchild). should somelike this: parent child grandchild (new treeview) parent grandchild great-grandchild child great-grandchild child grandchild grandchild it similar parent table mother , father went off , had new childern different spouse other spouse of there existing children. private sub populaterootlevel() ' query find first round of parent populatenodes(dt, jcatreeview.nodes) end sub private sub populatenodes(byval dt datatable, byval nodes treenodecollection) each dr datarow in dt.rows dim tn new treenode() tn.text = dr("title").tostring()...
Read more