Mr Gerard Kelly wrote:
Hello, I am a python beginner, and I have a question about scalars vs
arrays.
I am making a (very simple) code, and part of it is:
from numarray import *
from math import *
def source(x,y):
f=sin(x)
return f
a=4.
m=10
dx=a/(m+1.)
x=zeros([m,1], Float)
print x[0]
print func(x[0])
When I run this code, I get:
[ 0.]
0.0
However, if I change the line f=sin(x) to f=2*x, I will get:
[ 0.]
[ 0.]
Why does func(x[0]) return a scalar for sin(x), but returns an array for
2*x?
If I want a scalar returned for f=2*x, I need to put in func(x[0,0]).
Why do x[0] and x[0,0] both work for sin(x), but only x[0,0] will work
for 2*x?
sin() expects a scalar value.
x[0] is a 1 element array.
numarray magically converts the 1 element array to a scalar.
x[0]*2 multiplies each element of the array by 2 giving an array result.
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Bob Gailer
Chapel Hill NC
919-636-4239
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