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Questions tagged [symbolic-computation]

Symbolic computation or algebraic computation or computer algebra relates to algorithms and software for manipulating mathematical expressions and equations in symbolic form, as opposed to manipulating the approximations of specific numerical quantities represented by those symbols.

Symbolic computation or algebraic computation or computer algebra relates to algorithms and software for manipulating mathematical expressions and equations in symbolic form, as opposed to manipulating the approximations of specific numerical quantities represented by those symbols.

See http://en.wikipedia.org/wiki/Symbolic_computation

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Mincuts from graphs to find permutations that break the system into disjoint sets?

Assume an undirected system, graph where you want to find out elements in their permutations that makes the system disjoint such that each set is minimum. This graph has two special nodes: sink and source that cannot be in the elements. How can you…
hhh
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Multiply symbolic function by differential operator to create derivative

I have a matrix, A: A=[ x.^2 + y , 0; 0 , x.^2 + y ] I also have an operator matrix, D: D = [d/dx , 0; 0 , d/dy ] I want to be able to multiply D*A and end up with a matrix that looks like: B = [ diff(A(1,1),x) , 0 ; 0 …
Mike James Johnson
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How to tell maple that derivative of zero is zero when substituting?

I'm trying to use subs in maple to replace derivatives in a longer formula with 0: subs(diff(u(r),r) = 0, formula); It seems that if formula only involves first derivatives of u(r) this works as I expect. For example, formula :=…
Alec Jacobson
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Matlab symbolic solver giving different solution when I use subs to give values to consants and when I directly apply the numbers

My problem is the following (has to do with movement of vehicles) : I use dsolve in Matlab to solve a differential equation about the jerk (which is the derivative of the acceleration) and then I integrate the solution three times to get the…
jdous
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SymPy, how to perform exact symbolic representation (Rational Issue)?

So I'm planning to write a web application about math, and I need to convert user input to a SymPy expression without modifying it (Simplification), eg. so I'd like to cancel this behaviour like in this example. >>> srepr(Rational(2,4)) #this is the…
Onza
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Does symsum in Matlab do more than it should?

I have the following loop syms k m summ = symsum(k^2,k,1,m) for j=1:100 summ = subs(symsum((m-j)^2*summ,m,j+1,k),k,m); end and it takes about 600s to calculate it on R2014a, W7, 64b. An equivalent calculation in Mathematica takes 60s. The result…
user155002
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Matlab numerical error and how to get the correct answer

I somehow obtain the following expression in Matlab (R2014a on W7, 64b) 1/1034591578977116160000*prod(1:19)*(29576428208904825-17729494921579950*k - 20479697577410832*k^2 + 13867226524449248*k^3 - 836937224095392*k^4 - 869194297188672*k^5 +…
user155002
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Declare variables returned with symvar (MATLAB)

I'm trying to declare a function (n-dimensional) and its variables from an input, regardless of how many variables I have in this function. Example: input_func = '3*x*y^2 + x^3 -3*x' I use symvar to get these variables and it works just fine: >>…
igocps
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Solve Symbolic Function

I'm using syms variables so i can store the functions or polynomial for later calculation in script file. The problem is when i use subs to put value of syms variable into function or polynomial,it doesn't solve the functions completely.like >>syms…
Sameer Azeem
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Please explain the result from these commands

The code is syms x; v = @(x) (4 - x^2)^(1/2) - (2 - x)^(1/2)*(x + 2)^(1/2); ezplot(v(x),[-2,2]); which produce a plot Should not v(x) be zero for every x in [-2,2]?
epsilonxe
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Very slow infinite series with symsum in Matlab

I have the following infinite series which I need to evaluate. Currently, depending on the input parameters (kappa, sigmav, thetav) this functions takes very long to compute. Is there any possibility to speed it up? The time consuming expression is…
jcfrei
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A bug of numeric::solve

Consider syms x f(x); f = @(x) (x^2 - 4)^(1/2)/log(x^2)^2; The command solve(f(x)==0,x,'Real',true) returns ans = 2 -2 and I…
epsilonxe
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How can I define f(x) = x/x in MATLAB (Symbolic Computation)

I try with these commands x = sym('x'); f(x) = sym('f(x)'); f(x) = x/x; and f(x) = sym('x/x'); , but both of them produce f(x) = 1 (yes.. for every real x including 0) The question is how I can avoid the pre-evaluation in the command "sym", or…
epsilonxe
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MATLAB: Can you speed up solving a symbolic system of equations in a loop?

I'm trying to solve a symbolic system of equations for many variables. The structure of the equations will change based on the entries of AM, so solving these equations casually won't work well. This code does what I expect it to, however I need…
teh_allchemist
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MATLAB: (Good Ol') Error in MuPAD command

I know many a question like this has been asked before, but the cases that I've seen are more complicated (i.e. I don't understand them) and the answers seem to pertain only to the specific cases. My case is very simple (and thus broadly…
bongbang
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