Hi,
mpmath is for multi-precision math, not symbolic math. It's expecting
numbers, not symbols. I don't think there's a square root routine for
symbolic matrices implemented.
Cheers,
Tim.
On 24 Nov 2014, at 14:05, Yuxiang Wang wrote:
Dear all,
I have the following code to extract the square root of a symmetric
second-order tensor.
from sympy import symbols, Matrix, mpmathimport numpy as np
F11, F12, F13, F21, F22, F23, F31, F32, F33 = symbols('F11, F12, F13,
F21, F22, F23, F31, F32, F33', real=True)
F = np.array([[F11, F12, F13], [F21, F22, F23], [F31, F32, F33]])
B = F.dot(F.T)
mpmath.sqrtm(Matrix(B))
However, it gave me the error:
TypeError Traceback (most recent call
last)<ipython-input-14-439fed475a57> in <module>()
5 F = np.array([[F11, F12, F13], [F21, F22, F23], [F31, F32, F33]])
6 B = F.dot(F.T)----> 7 mpmath.sqrtm(Matrix(B))
X:\WinPython3\python-3.4.2.amd64\lib\site-packages\sympy\mpmath\matrices\calculus.py
in sqrtm(ctx, A, _may_rotate)
308
309 """
--> 310 A = ctx.matrix(A)
311 # Trivial
312 if A*0 == A:
X:\WinPython3\python-3.4.2.amd64\lib\site-packages\sympy\mpmath\matrices\matrices.py
in __init__(self, *args, **kwargs)
326 A[i,j] = convert(A[i,j])
327 elif hasattr(args[0], 'tolist'):
--> 328 A = self.ctx.matrix(args[0].tolist())
329 self.__data = A._matrix__data
330 self.__rows = A._matrix__rows
X:\WinPython3\python-3.4.2.amd64\lib\site-packages\sympy\mpmath\matrices\matrices.py
in __init__(self, *args, **kwargs)
299 for i, row in enumerate(A):
300 for j, a in enumerate(row):
--> 301 self[i, j] = convert(a)
302 else:
303 # interpret list as row vector
X:\WinPython3\python-3.4.2.amd64\lib\site-packages\sympy\mpmath\ctx_mp_python.py
in convert(ctx, x, strings)
660 if hasattr(x, '_mpmath_'):
661 return ctx.convert(x._mpmath_(prec, rounding))
--> 662 return ctx._convert_fallback(x, strings)
663
664 def isnan(ctx, x):
X:\WinPython3\python-3.4.2.amd64\lib\site-packages\sympy\mpmath\ctx_mp.py
in _convert_fallback(ctx, x, strings)
612 else:
613 raise ValueError("can only create mpf from
zero-width interval")
--> 614 raise TypeError("cannot create mpf from " + repr(x))
615
616 def mpmathify(ctx, *args, **kwargs):
TypeError: cannot create mpf from F11**2 + F12**2 + F13**2
May I ask why that is happening? Is this a limitation of sympy or that
I am
doing something wrong?
Thank you!
Shawn
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