function handling - Printable Version

function handling - Printable Version

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function handling - JohnCrichton - Sep-06-2017

Hi All!
I'm pretty new to Python coding and I'm doing some stuff while I learn the language, I have some experience with Matlab especially for mathematical computation so I'm not totally new to coding.

But here is my problem:

I have made a function that solves f(x) = 0 and returns x. It is a standard bysection method and it works well.

What I have done so far was to define a function that I then fed to the bysection:

def my_fun(x):
y = x*2 + 4
return y

def main()
x = bysection(my_fun)
print(x)
return

This configuration WORKS, it gives me back the correct x and produces no errors.

The problem is when I want to have my_fun function of a parameter as well.

def my_fun(x, b):
y = x*2 + b
return y

The bisection function solves only f(x) = 0 and not f(x,b) = 0. What I want to do is to pass to the bysection my_fun where x is free and b is assigned:

def main()
b = 4
x = bysection(my_fun(x, b))
print(x)
return

Of course this doesn't work, do you guys have any idea? Matlab allowed me to define the function INSIDE the main, so b was already assigned, but in Python I have to define the function and then assign only b but keeping x as the only variable.

Basically can I go from:

function(x,b) to function(x) by assigning a value for b?

Thanks in advance for your help!

RE: function handling - ichabod801 - Sep-07-2017

First, give b a default:

def my_fun(x, b = 1):
    y = x * 2 + b
    return y

Then make a function wrapper:

def set_b(my_func, b):
    def b_set(x):
        return my_func(x, b = b)
    return b_set

Then, wrap the function:

def main():
    b = 4
    x = bysection(set_b(my_fun, b))
    print(x)

Then, read the BBCode link in my signature (below) to learn how to use python tags in your own posts.

RE: function handling - JohnCrichton - Sep-07-2017

That works just about right, thank you very much for your help!