if len(diagonals) == 0 or isscalarlike(diagonals[0]):解释len() of unsized object
时间: 2024-06-04 08:10:59 浏览: 19
The error message "len() of unsized object" means that the object being passed to the len() function does not have a defined length or size. This usually occurs when the object is not iterable or does not support the len() method.
In this specific code snippet, the error occurs because the variable "diagonals" has not been initialized or has been initialized as an empty object, thus it does not have a defined length. The condition "len(diagonals) == 0" checks if the length of diagonals is equal to zero or if diagonals is an empty object. If either of these conditions is true, the subsequent code block will execute.
相关问题
if len(diagonals) == 0 or isscalarlike(diagonals[0]):
This line of code checks if the length of the list called "diagonals" is 0 or if the first element of the list is a scalar (a single value, like an integer or float).
If the length of the list is 0, it means there are no diagonals in the matrix and the code will likely proceed to calculate the diagonal elements in some way.
If the first element of the list is a scalar, it means that the diagonals are not given as a list but rather as a single value that applies to all diagonal elements in the matrix. In this case, the code will likely use this scalar value to populate all diagonal elements in the matrix.
A given parallelogram ABCD, M is the intersection point of the diagonals of AC and BD, for any given point O, Proof that .
To prove that OM is perpendicular to AB, we need to show that the dot product of OM and AB is zero.
Let's first find the coordinates of M. We know that M is the intersection point of AC and BD, so we can find M by solving the system of equations:
x/3 + y/2 = 1 (equation of AC)
x/2 + y/3 = 1 (equation of BD)
Solving these equations, we get:
x = 6/5
y = 6/5
Therefore, the coordinates of M are (6/5, 6/5).
Now, let's find the vectors OM and AB.
OM = M - O = (6/5 - x, 6/5 - y) - (x, y) = (1/5 - x, 1/5 - y)
AB = B - A = (3, 0) - (0, 2) = (3, -2)
The dot product of OM and AB is:
OM · AB = (1/5 - x)(3) + (1/5 - y)(-2)
Substituting the values of x and y, we get:
OM · AB = (1/5 - 6/5)(3) + (1/5 - 6/5)(-2) = 0
Therefore, OM is perpendicular to AB.
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