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Integral sinc(x)

ttokoro
20-Turquoise

Integral sinc(x)

Quora shows interesting math. Prime 7 can show third equation is also pi.

I want to calculate until

ttokoro_0-1633168449646.png

and 

ttokoro_1-1633168484513.png does not show pi/2

 

 

image.pngimage.pngimage.png need very long time to solve.

1 ACCEPTED SOLUTION

Accepted Solutions
ttokoro
20-Turquoise
(To:-MFra-)

10 REPLIES 10
-MFra-
21-Topaz II
(To:ttokoro)

Please note that the definition of Mathcad's sinc function differs from that used elsewhere. The Mathcad definition is sinc(x) = sin(x)/x, while on certain texts it is defined like this: sinc(x) = sin(πx) / (πx) so in the comparison of the calculated values and those of the text there may be differences. I'm referring to Mathcad 15. Certain errors in MC15 have been fixed in Prime 7.

answer to ttokoro.jpg

LucMeekes
23-Emerald III
(To:-MFra-)

Maple says:

LucMeekes_1-1633257613804.png

 

Luc

LucMeekes
23-Emerald III
(To:ttokoro)

LucMeekes_0-1633257003438.png

Luc

ttokoro
20-Turquoise
(To:LucMeekes)

image.png

This is limit of Prime 7.

 

ttokoro_0-1633432265030.png

Therefore, I can't get the results shown by Quora web site.

 

ttokoro_1-1633432425598.png

 

 

-MFra-
21-Topaz II
(To:ttokoro)

answer to ttokoro 1.jpg

ttokoro
20-Turquoise
(To:-MFra-)

image.pngimage.png TOL=10^-3

ttokoro_0-1633562726618.pngTOL=10^-7

 

image.pngimage.pngimage.png

Therefore, Quora and Luc show the answer is pi/2 for n=0 to 6. But n>6 are not calculate symbolically when using 15 digit accuracy. May be n>6 also show pi/2 symbolically when calculate more digit accuracy. Or Quora is true mathematically.

-MFra-
21-Topaz II
(To:ttokoro)

I use the sinc function according to the definition of the text reported here below. Sin (x) / x is something else ...

The Fourier.jpg

ttokoro
20-Turquoise
(To:-MFra-)

LucMeekes
23-Emerald III
(To:-MFra-)

The sinc function is not included in the ISO standard for mathematical functions, ISO 80000-2:2013, nor in its 2019 update.

The 'NIST Handbook of mathematical functions' defines the Sinc function:

LucMeekes_0-1633613716574.png

(but that's not the sinc function...)

 

There's a difference between the sinc function and the normalised sinc function according to Wikipedia. Follow the link to Rayleigh's formula to find how it was originally defined...

 

Success!
Luc

VladimirN
24-Ruby II
(To:ttokoro)

When I try to solve it (Mathcad 15 F000, Windows 7 x64, 16 GB of RAM), I get an error - "Internal error [1321]":

 

Pic-1.png

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