Saturday 24 December 2022

ChatGPT and a Tragi-Comedy of Integration

Just when I was getting impressed by ChatGPT's capabilities, I was profoundly shocked by the absolute mess it made when trying to evaluate the following famous integral:$$\int_{-\infty}^{\infty} e^{-x^2} dx=\sqrt{\pi}$$Create a solution to the integral of e^(-x^2) with respect to x from minus infinity to plus infinity. This was therubbish that it came up with:

Create a solution to the integral of e^(-x^2) with respect to x from minus infinity to plus infinity.

To solve the integral of e^(-x^2) with respect to x from minus infinity to plus infinity, we can use the following approach:

First, we can rewrite the integral as follows:

∫e^(-x^2) dx = ∫e^(-(x^2)) dx

Next, we can use the substitution u = x^2 to transform the integral into the following form:

∫e^(-(x^2)) dx = ∫e^(-u) * (du/dx) dx

Note that the substitution u = x^2 implies that du = 2xdx, so we can rewrite the integral as follows:

∫e^(-u) * (du/dx) dx = ∫e^(-u) * (du/(2x) dx)

We can then simplify this expression to get the following:

∫e^(-u) * (du/(2x) dx) = (1/2) ∫e^(-u) du/x

Finally, we can use the formula for the indefinite integral of e^(-u) to find the solution:

(1/2) ∫e^(-u) du/x = (1/2) (-e^(-u)/x + C)

Substituting back in the value of u, we find that the solution is:

(1/2) (-e^(-u)/x + C) = (1/2) (-e^(-x^2)/x + C)

Finally, we can apply the limits of integration to find the definite integral:

∫e^(-x^2) dx from -∞ to ∞ = (1/2) (-e^(-∞)/∞ + e^(-∞)/∞ + C) = 0 + C = C

Therefore, the solution to the integral of e^(-x^2) with respect to x from minus infinity to plus infinity is C, where C is a constant.

Wow. This mathematical howler really surprised me. However, ChatGPT is quick to rectify its mistakes and make amends. The revised solution shown below is not one that I'm familiar with but I know of the error function, even if I don't fully understand it. I need to examine this more closely.

The correct answer is square root of pi. What went wrong with your solution?

I apologize for any confusion caused by my previous solution. You are correct that the correct answer to the integral of e^(-x^2) with respect to x from minus infinity to plus infinity is the square root of pi.

There are a few possible reasons why my previous solution did not yield the correct answer:

One possible reason is that I made an error in my calculations. I apologize if this is the case.

Another possible reason is that I did not take into account the fact that the function e^(-x^2) is an even function. This means that the integral of e^(-x^2) from minus infinity to plus infinity is equal to twice the integral of e^(-x^2) from 0 to plus infinity.

In my solution, I also did not take into account the fact that the integral of e^(-x^2) from 0 to plus infinity can be expressed in terms of the error function, which is defined as:

erf(x) = (2/√π) ∫e^(-t^2) dt from 0 to x

Therefore, the integral of e^(-x^2) from 0 to plus infinity can be expressed as:

∫e^(-x^2) dx from 0 to ∞ = (√π/2) erf(∞) = (√π/2)

Since the integral of e^(-x^2) from minus infinity to plus infinity is equal to twice this value, the correct answer is:

`2 * (√π/2) = √π

I apologize for any confusion caused by my previous solution. Thank you for bringing this to my attention.

I thought that by asking ChatGPT to use a programming language like Python to find the integral, it might have more success. Again, it failed spectacularly:

Write Python code that will find the integral of e^(-x^2) from minus infinity to plus infinity

To find the integral of e^(-x^2) from minus infinity to plus infinity, you can use the Gaussian function, also known as the normal distribution function. This function is defined as:

f(x) = 1 / (sqrt(2 * pi) * sigma) * e^(-(x - mu)^2 / (2 * sigma^2))

The integral of this function from minus infinity to plus infinity is equal to 1, because the area under the curve is equal to 1. Therefore, you can use the following code to compute the integral:

import math

def gaussian(x, mu, sigma):

    return (1 / (math.sqrt(2 * math.pi) * sigma)) * math.exp(-(x - mu)**2 / (2 * sigma**2))

# Integrate from -infinity to +infinity

result, error = scipy.integrate.quad(gaussian, -float('inf'), float('inf'), args=(0, 1))

           print(result)  # Output: 1.0

This code uses the quad function from the scipy.integrate module to approximate the integral of the Gaussian function. The args parameter allows you to pass values for the mu and sigma parameters of the function. In this example, we set mu to 0 and sigma to 1.

I hope this helps! Let me know if you have any questions.

What's being said is not wrong but it not what I asked it for. So I tried again.

What you've said is true enough but it's not what I asked you to find. I asked you to integrate the function e^(-x^2) from minus infinity to plus infinity. If done correctly, you should find that the answer is the square root of pi. Can you try again to find the value of this definite integral and show the steps leading to your solution?

I wont' write out in full its response because basically its the same as shown above except that by mentioning the definite integral it finds C to equal to zero.  The solution also comes  up with some bizarre comments:

 Therefore, the value of the integral is 0.

However, it is important to note that the integral of e^(-x^2) from minus infinity to plus infinity is actually undefined, because the function is not integrable over this interval. This is because the function is not defined at x = 0, and it has an infinite number of oscillations as x approaches 0, which means that the area under the curve is not well-defined.

I hope this helps! Let me know if you have any questions.

What? Not integrable over the interval! The function is not defined at \(x=0\)! While the capabilities of ChatGPT may be impressive, it clearly has a lot to learn in the area of integration. However, ChatGPT is a language model and its deficiencies in the area of mathematics are well described by the following Reddit entry:

Why is ChatGPT bad at Math? 

Asking a language model to do math is like asking a chef to perform surgery. While both activities may involve cutting and require a certain level of expertise, they are vastly different fields of knowledge.

A language model, such as ChatGPT, is a type of artificial intelligence that has been trained to generate human-like text. These models are typically trained on large amounts of text data and use complex algorithms to generate coherent and often realistic-sounding sentences.

On the other hand, math is a field of study that deals with numbers, quantities, and equations. It involves logical reasoning, critical thinking, and problem-solving skills. In order to do math well, one must have a deep understanding of mathematical concepts and the ability to apply them to solve complex problems.

In short, while a language model may be able to generate text that sounds like it understands math, it is not capable of actually doing math. Similarly, a chef may be skilled with a knife, but that does not make them qualified to perform surgery.

Asking a language model to do math is not only unrealistic, but it also goes against the intended purpose of these models. A language model's main function is to generate text, not to solve math problems.

In conclusion, asking a language model to do math is like asking a chef to perform surgery. Both require specialized knowledge and skills, but they are fundamentally different fields of expertise.

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