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Over the past years in math, I've seen many different methods for reparametrizing variables as a way to make a complex integral easier to deal with. Essentially we just take a function of some value and differentiate it with respect to a different variable, creating newer, simpler functions. One application of this includes u-substitution, where we let an arbitrary variable (in this case "u") represent a portion of our integral. For example, let's take this integral:
 
Over the past years in math, I've seen many different methods for reparametrizing variables as a way to make a complex integral easier to deal with. Essentially we just take a function of some value and differentiate it with respect to a different variable, creating newer, simpler functions. One application of this includes u-substitution, where we let an arbitrary variable (in this case "u") represent a portion of our integral. For example, let's take this integral:
<center><math> \int {sinx*cosx} </math></center>
+
<center><math> \int {(sin(x))*(cos(x))} dx </math></center>
 
, and we even see parametrization appear in surface integrals.  
 
, and we even see parametrization appear in surface integrals.  
  

Revision as of 16:12, 27 November 2020

A Review on Reparametrizing

Over the past years in math, I've seen many different methods for reparametrizing variables as a way to make a complex integral easier to deal with. Essentially we just take a function of some value and differentiate it with respect to a different variable, creating newer, simpler functions. One application of this includes u-substitution, where we let an arbitrary variable (in this case "u") represent a portion of our integral. For example, let's take this integral:

$ \int {(sin(x))*(cos(x))} dx $

, and we even see parametrization appear in surface integrals.

Feynman's Technique to integration utilizes parametrization and a combination with other different mathematical properties in order to integrate an integral that is can't be integrated through normal processes like u-substitution or integration by parts. It primarily focuses on setting a function equal to an integral, and then differentiating the function to get an integral that is easier to work with. A simple example would be: (1/2)*xe^(x^2) instead of just e^(x^2).

Back to Feynman Integrals

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