symbolic-math

I am having a lot of trouble trying to make symbolic substitution go faster - that is, substituting in for variables in a symbolic expression and getting out a double. I am creating a complicated function f, and calculating its jacobian df. This goes at a reasonable pace, and I can save it to a file just fine. But when I try to use matlabFunction or even disp or fprintf, the system hangs and is unable to proceed further (even when matlabFunction is set to unoptimized). This is a major problem as I need to be able to do reasonably fast substitution. The f vector is 24 elements, and the Jacobian

From my SymPy output I have the matrix shown below, which I must integrate in 2D. Currently I am doing it element-wise as shown below. This method works but it gets too slow (for both sympy.mpmath.quad and scipy.integrate.dblquad ) for my real case (in which A and its functions are much bigger (see edit below): from sympy import Matrix, sin, cos import sympy import scipy sympy.var( 'x, t' ) A = Matrix([[(sin(2-0.1*x)*sin(t)*x+cos(2-0.1*x)*cos(t)*x)*cos(3-0.1*x)*cos(t)], [(cos(2-0.1*x)*sin(t)*x+sin(2-0.1*x)*cos(t)*x)*sin(3-0.1*x)*cos(t)], [(cos(2-0.1*x)*sin(t)*x+cos(2-0.1*x)*sin(t)*x)*sin(3-0.1

I am building (my first...) MatLab program, it needs to differentiate an equations symbolically and then use this solution many many times (with different numeric inputs). I do not want it to recalculate the symbolic differentiation every time it needs to put in a new set of numeric values. This would probably greatly add to the time taken to run this program (which - given its nature, a numeric optimiser, will probably already be hours). My question is how can I structure my program such that it will not recalculate the symbolic differentiation? The class in question is: function [ result ] =

I am trying to use the package Ryacas in R . Here what is going on: > install.packages("Ryacas") --- Please select a CRAN mirror for use in this session --- trying URL 'http://www.stats.bris.ac.uk/R/bin/windows/contrib/2.14/Ryacas_0.2-11.zip' Content type 'application/zip' length 263424 bytes (257 Kb) opened URL downloaded 257 Kb package ‘Ryacas’ successfully unpacked and MD5 sums checked The downloaded packages are in C:\Documents and Settings\yogcal\Local Settings\Temp\RtmpKeuu7m\downloaded_packages Then I try to load Ryacas : > library(Ryacas) Loading required package: XML C:\Program Files

Say I have a anonymous function f = @(x) x^2 and I want to convert this to a symbolic function. Is there a built in command for that? You could just pass it to SYM: f = @(x) x^2; g = sym(f) But then most of the symbolic functions do that automatically when they receive a function handle ( subs , int , etc...) 来源： https://stackoverflow.com/questions/11322295/how-do-i-convert-an-anonymous-function-to-a-symbolic-function-in-matlab

I'm doing a very simple probability calculations of getting subset of X, Y, Z from set of A-Z (with corresponding probabilities x, y, z). And because of very heavy formulas, in order to handle them, I'm trying to simplify (or collect or factor - I dont know the exact definition) these polynomial expressions using sympy . So.. having this (a very simple probability calculation expression of getting subset of X,Y,Z from set of A-Z with corresponding probabilities x, y, z) import sympy as sp x, y, z = sp.symbols('x y z') expression = ( x * (1 - x) * y * (1 - x - y) * z + x * (1 - x) * z * (1 - x