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I have poly in MuPAD (one variable, several parameters). I want to extract it somehow to Matlab.

An example of poly in MuPAD:

poly((-7/(2*k^2))*X^2 + ((7*(b + k))/(2*k^2) + (7*(b + 2*k))/(2*k^2) + 4/k)*X + (- (b + k)*((7*(b + 2*k))/(2*k^2) + 4/k) + 1), [X])

I want to get it in Matlab:

x*((7*(b + k))/(2*k^2) + (7*(b + 2*k))/(2*k^2) + 4/k) - (7*x^2)/(2*k^2) - (b + k)*((7*(b + 2*k))/(2*k^2) + 4/k) + 1

Is there any handy way to do this? P.S. Matlab R2015a

Gleb Makarchuk
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    To whoever marked this as unclear: This question is perfectly clear – perhaps you've never used MuPAD? – horchler Oct 28 '15 at 14:25

2 Answers2

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I believe that you want to convert the MuPAD object of domain DOM_POLY to a general symbolic expression. You can use the expr function for this. I'm assuming that you're already working from within Matlab here (from within MuPAD, it's just expr(p1)):

syms b k X
p1 = feval(symengine,'poly',(-7/(2*k^2))*X^2 + ((7*(b + k))/(2*k^2) + (7*(b + 2*k))/(2*k^2) + 4/k)*X + (- (b + k)*((7*(b + 2*k))/(2*k^2) + 4/k) + 1),'[X]')
p2 = feval(symengine,'expr',p1)

which returns

p2 =

X*((7*b + 7*k)/(2*k^2) + (7*b + 14*k)/(2*k^2) + 4/k) - (b + k)*((7*b + 14*k)/(2*k^2) + 4/k) - (7*X^2)/(2*k^2) + 1

You can also use matlabFunction to convert either form (p1 or p2 above) to a vectorized floating point function handle, e.g.:

f = matlabFunction(p1,'Vars',{b k X})

which returns

f = 

    @(b,k,X)-(b+k).*(1.0./k.^2.*(b.*7.0+k.*1.4e1).*(1.0./2.0)+4.0./k)+X.*(1.0./k.^2.*(b.*7.0+k.*7.0).*(1.0./2.0)+1.0./k.^2.*(b.*7.0+k.*1.4e1).*(1.0./2.0)+4.0./k)-X.^2.*1.0./k.^2.*(7.0./2.0)+1.0
horchler
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You can use the generate::MATLAB function to create the MATLAB code for any expression. To print the function call (without quotes), you can use print. A small example:

p := -7*X^2 + 8*X + 1
print(Unquoted, generate::MATLAB(p))

returns 

t0 = X*8.0-X^2*7.0+1.0;

which is the correct MATLAB syntax for this function.

hbaderts
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