Evaluating Definite Integrals with Floor Function

In summary, the conversation discusses the evaluation of two integrals, $\displaystyle \int_{0}^{\pi}\lfloor \cot x \rfloor dx$ and $\displaystyle \int_{0}^{\pi}\lfloor \cos x \rfloor dx$, where $\lfloor x \rfloor$ represents the floor function of $x$. By treating the integrals as 'improper', the solution involves a telescopic sum. The final result for the first integral is $-\frac{\pi}{2}$.
  • #1
juantheron
247
1
Evaluation of \(\displaystyle \displaystyle \int_{0}^{\pi}\lfloor \cot x \rfloor dx\) and \(\displaystyle \displaystyle \int_{0}^{\pi}\lfloor \cos x \rfloor dx\;,\) where \(\displaystyle \lfloor x \rfloor \) denote Floor function of \(\displaystyle x\)
 
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  • #2
jacks said:
Evaluation of \(\displaystyle \displaystyle \int_{0}^{\pi}\lfloor \cot x \rfloor dx\) and \(\displaystyle \displaystyle \int_{0}^{\pi}\lfloor \cos x \rfloor dx\;,\) where \(\displaystyle \lfloor x \rfloor \) denote Floor function of \(\displaystyle x\)

[sp]By treating the integral as 'improper' You obtain a telescopic sum...

$\displaystyle \int_{0}^{\pi} \lfloor \cot x \rfloor dx = \int_{- \frac{\pi}{2}}^{\frac{\pi}{2}} \lfloor \tan x \rfloor dx = \lim_{n \rightarrow \infty} \tan^{-1} 0 - \tan^{-1} 1 + \tan^{-1} 1 - \tan^{-1} 2 + ... + \tan^{-1} (n-1) - \tan^{-1} n = - \frac{\pi}{2}$ [/sp]

Kind regards

$\chi$ $\sigma$
 

FAQ: Evaluating Definite Integrals with Floor Function

What is the definition of the floor function?

The floor function, denoted by ⌊x⌋, is a mathematical function that rounds down a given number to the nearest integer. For example, ⌊3.7⌋ = 3 and ⌊-2.5⌋ = -3.

How do you evaluate a definite integral with a floor function?

To evaluate a definite integral with a floor function, you first need to rewrite the integral using the floor function as a piecewise function. Then, you can split the integral into smaller subintervals where the floor function is constant and evaluate each subinterval separately.

Can the floor function be used to approximate integrals?

Yes, the floor function can be used to approximate integrals by using the Riemann sum method. This involves dividing the interval into smaller subintervals, using the floor function to find the height of each rectangle, and then taking the limit as the number of subintervals approaches infinity.

What are the main properties of the floor function?

The main properties of the floor function include: 1) ⌊x⌋ ≤ x for all x, 2) ⌊x+y⌋ = ⌊x⌋ + ⌊y⌋ for all x and y, 3) ⌊cx⌋ = c⌊x⌋ for any constant c, and 4) the floor function is not continuous at integers, but is continuous at all other points.

How can the floor function be used in real-world applications?

The floor function can be used in real-world applications such as in computer programming and in financial calculations. In computer programming, the floor function can be used to round down a number to the nearest integer, which is useful for tasks such as converting decimal numbers into whole numbers. In finance, the floor function can be used to calculate the number of shares to buy or sell in a stock market transaction.

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