如何使我的分段函数在 python 中提供的间隔之外为零
How to make my Piecewise function zero outside the provided interval in python
这是我的代码:
In [61]: import sympy as sp
In [62]: x = sp.Symbol('x')
In [63]: phi_1 = sp.Piecewise( ( (1.3-x)/0.3, 1<=x <=1.3 ))
In [64]: phi_1.subs(x,1.2)
Out[64]: 0.333333333333334
In [65]: phi_1.subs(x,1.4)
Out[65]: Piecewise()
更具体地说,我想得到零作为输入编号的答案。 65,因为 1.4 在区间 [1, 1.3].
之外
您需要告诉 Piecewise
您希望函数在超出范围时求值为零,例如:
import sympy as sp
x = sp.Symbol('x')
phi_1 = sp.Piecewise(
(0, x < 1),
(0, x > 1.3),
( (1.3-x)/0.3, True )
)
print(phi_1.subs(x,1.2)) # 0.333333333333334
print(phi_1.subs(x,1.4)) # 0
请注意,此语法在 0.7.1 和 0.7.6 中有效——您的代码在 0.7.6 中使用 "compound conditional" 1 <=x <=1.3
引发了 TypeError
这是我的代码:
In [61]: import sympy as sp
In [62]: x = sp.Symbol('x')
In [63]: phi_1 = sp.Piecewise( ( (1.3-x)/0.3, 1<=x <=1.3 ))
In [64]: phi_1.subs(x,1.2)
Out[64]: 0.333333333333334
In [65]: phi_1.subs(x,1.4)
Out[65]: Piecewise()
更具体地说,我想得到零作为输入编号的答案。 65,因为 1.4 在区间 [1, 1.3].
之外您需要告诉 Piecewise
您希望函数在超出范围时求值为零,例如:
import sympy as sp
x = sp.Symbol('x')
phi_1 = sp.Piecewise(
(0, x < 1),
(0, x > 1.3),
( (1.3-x)/0.3, True )
)
print(phi_1.subs(x,1.2)) # 0.333333333333334
print(phi_1.subs(x,1.4)) # 0
请注意,此语法在 0.7.1 和 0.7.6 中有效——您的代码在 0.7.6 中使用 "compound conditional" 1 <=x <=1.3
TypeError