CODEWITHSUNDEEP
pythonarrayslistcomplex-numbers
Hey There
Hey There

Reputation: 275

Having trouble to get the real part of an array obtained from the fun.eval

I used the eval function to evaluate a function. the code is written below:

import numpy as np
import sympy
from sympy import Symbol, Add
s = sympy.Symbol('s')
x = [ s, s+1, 10*s**2, 5]
a = [1 + 1j, 2 , 3 , 4 , 5]
fun = Add(*x) # Create a function by adding all terms. * is to unpack all the values

def F(fun, v):
    return fun.evalf(subs={s: v}) # Evaluate the function at s=v

f_dis = [F(fun, v) for v in a] 
print (f_dis)
fit3 = np.asanyarray(f_dis)
print ("fit3 =", fit3)
realpart = fit3.real[0]
print ("real =", realpart)

the result of f_dis is 

[8.0 + 22.0*I, 50.0000000000000, 102.000000000000, 174.000000000000, 266.000000000000]

The point here is that the code shows the 8.0 + 22.0*I as the real part of the first element, instead of showing 8 only. What should I do to solve this issue? Thanks.

Upvotes: 1

Views: 38

Answers (1)

Sheldore
Sheldore

Reputation: 39052

You can use re from Sympy to get only the real part of the evaluated expression

import numpy as np
from sympy import Symbol, Add, re

s = Symbol('s')
x = [ s, s+1, 10*s**2, 5]
a = [1 + 1j, 2 , 3 , 4 , 5]
fun = Add(*x) # Create a function by adding all terms. * is to unpack all the values

def F(fun, v):
    return fun.evalf(subs={s: v}) # Evaluate the function at s=v

f_dis = [re(F(fun, v)) for v in a] # <---- Use re() here
print (f_dis)
# [8.00000000000000, 50.0000000000000, 102.000000000000, 174.000000000000, 266.000000000000]

Upvotes: 1

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