equation-solving

I'm trying to code a program that solves systems of equations in MATLAB. I was wondering if there is a way to get MATLAB to group like terms and put their coefficients into a matrix? I realize that I can just enter the coefficients in by hand but I want to hopefully repurpose this small program to perform nodal analysis. You could always use my sympoly tools to do much of the work for you. Since this set of tools will give you direct access to the parsed result, this will make your life easier, as well as do much symbolic manipulation of an expression. For example... >>sympoly x y z >> P = 3*x

I am trying to use solve() to solve a system of equations of the following form eq1=a1x+a2y; eq2=b1x+b2y; where a1 = .05 for values of x<5 , .1 for values of 5 Is there a way to solve for this using solve? As in sol = solve(eq1,eq2); I'm not sure what you're trying to do here. Can you please post a real example (with numbers) and what you would like the output to be? I think you're trying to solve linear simultaeneous equations. Assuming that is what you are trying to do: I would suggest multiplying all of your equations by 20, so that your minimum quanta size of 0.05 becomes 1.00 . Your

Assuming I have the following four equations: cos(x)/x = a cos(y)/y = b a + b = 1 c sinc(x) = d sinc(y) for unknown variables x, y, a and b . Note that cos(x)/x=a has multiple solutions. Similar goes for variable y . I am only interested in x and y values, which are first positive roots (if that matters). You can safely assume a, b, c and d are known real constants, all positive. In Mathematica the code to solve this would look something like: FindRoot[{Cos[x]/x == 0.2 a + 0.1, Cos[y]/y == 0.2 b + 0.1, a + b == 1.0, 1.03*Sinc[x] == Sinc[y]*1.02}, {{x, .1}, {y, .1}, {a, .3}, {b, .1}}] which as

I have a equation system and I want to solve it using numerical methods. I want to get a close solution given a starting seed. Let me explain. I have a vector of constants , X , of values: X <- (c(1,-2,3,4)) and a vector W of weights: W <- (c(0.25,0.25,0.25,0.25)) I want that the sum of the components of W will be ( sum(W)=1 ), and the sum of the multiplication of X and W element by element will be a given number N ( sum(W*X)=N ). Is there a easy way to do this in R? I have it in Excel, using Solver, but I need to automatize it. Here is your constant and your target value: x <- c(1, -2, 3, 4)

I recently rediscovered a small package by Roman Maeder that tells Mathematica to automatically thread arithmetic and similar functions over expressions such as x == y. Link to Maeder's package. First, to demonstrate, here's an example given by Maeder: In[1]:= Needs["EqualThread`"] Now proceed to use the threading behavior to solve the following equation for x 'by hand': In[7]:= a == b Log[2 x] In[8]:= %/b Out[8]:= a/b == Log[2 x] Now exponentiate: In[9]:= Exp[%] Out[9]= E^(a/b) == 2 x And divide through by 2: In[10]:= %/2 Out[10]= (E^(a/b))/2 == x Q: From a design perspective, can someone