CODEWITHSUNDEEP
python
Sartorible
Sartorible

Reputation: 356

How do I convert a complex number?

I built a calculator for a bio equation, and I think I've narrowed down the source of my problem, which is a natural log I take:

goldman = ((R * T) / F) * cmath.log(float(top_row) / float(bot_row))

print("Membrane potential: " + str(goldman) + "V"

My problem is that it will only display the output in a complex form:

Membrane potential: (0.005100608207126714+0j)V

Is there any way of getting this to print as a floating number? Nothing I've tried has worked.

Upvotes: 18

Views: 57121

Answers (4)

Saud Qureshi
Saud Qureshi

Reputation: 1

It is simple if you need only real part of the complex number.

goldman = 0.005100608207126714+0j  
print(goldman)  
(0.005100608207126714+0j)  

goldman = float(goldman.real)  
print(goldman)  
0.005100608207126714

If you need absolute value then use following

goldman = 0.005100608207126714+0j  
print(goldman)  
(0.005100608207126714+0j)  

goldman = float(abs(goldman))  
print(goldman)  
0.005100608207126714  
print(type(goldman))  
<class 'float'>

Upvotes: 0

Rakshit Bhagwat Kathawate
Rakshit Bhagwat Kathawate

Reputation: 21

If you want to just convert it to float value you can do this:

def print_float(x1):
a=x1.real
b=x1.imag
val=a+b
print(val)

ec=complex(2,3)

In this way you can actually get the floating value.

Upvotes: 2

tom10
tom10

Reputation: 69182

Use math.log instead of cmath.log.

Since you don't want the imaginary part of the result, it would be better to use math.log instead of cmath.log. This way, you'll get an error if your input is not in the valid domain for a real log, which is much better than silently giving you meaningless results (for example, if top_row is negative). Also, complex numbered results make no sense for this particular equation.

ie, use:

goldman = ((R * T) / F) * math.log(float(top_row) / float(bot_row))

Upvotes: 7

mgilson
mgilson

Reputation: 309919

Complex numbers have a real part and an imaginary part:

>>> c = complex(1, 0)
>>> c
(1+0j)
>>> c.real
1.0

It looks like you just want the real part... so:

print("Membrane potential: " + str(goldman.real) + "V"

Upvotes: 22

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