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Integral of sec^2(x)

jstavitsky
1-Newbie

Integral of sec^2(x)

Perhaps I am inputting incorrectly but this is what I get

55da60a1bc4da.png

1 ACCEPTED SOLUTION

Accepted Solutions
lturek
4-Participant
(To:jstavitsky)

Can't be sure as you don't attach your sheet, but it looks like you have an invisible implicit multiplication operator between "sec" and the parentheses. So your integrands are "sec^2*x" and "sec*x^2", where "sec" is treated as an unknown.

If you fix that it should work as expected:

You  can't use the first notation. While its a quite common and useful shortcut its not perfectly correct to just square the function name and so Mathcad does not accept it. In fact you even should not be able to enter it that way. Its probably from your try to enter it anyway which resulted in separating the function name from the argument and created that implicit multiplication.

If you really need that kind of notation, you could define a custom function for the square of sec but its not that good looking.

LT

View solution in original post

6 REPLIES 6
lturek
4-Participant
(To:jstavitsky)

Can't be sure as you don't attach your sheet, but it looks like you have an invisible implicit multiplication operator between "sec" and the parentheses. So your integrands are "sec^2*x" and "sec*x^2", where "sec" is treated as an unknown.

If you fix that it should work as expected:

You  can't use the first notation. While its a quite common and useful shortcut its not perfectly correct to just square the function name and so Mathcad does not accept it. In fact you even should not be able to enter it that way. Its probably from your try to enter it anyway which resulted in separating the function name from the argument and created that implicit multiplication.

If you really need that kind of notation, you could define a custom function for the square of sec but its not that good looking.

LT

Yea it was fine without the brackets - I cant really say why I thought  putting the power outside the parens would cause problems

Thanks again

RichardJ
19-Tanzanite
(To:lturek)

You  can't use the first notation.

Oh yes you can . It is a little documented (or undocumented?) feature of Mathcad. For certain trigonometric functions you can use the prefix operator with the function name squared in the first placeholder, and the variable in the second placeholder.

You don't even need the parentheses around the variable!

lturek
4-Participant
(To:RichardJ)

???

WTF, why can't I quote your message when I am in "Advanced mode" and how can i switch back to "normal(?) mode"? This new forum design sure is a pita.

Anyway -Wow! Never would have thought of that trick. And it really seems to work for just a few selected functions. When I try it with "log" or "ln" I get the error message that "This function requires 1 argument but is applied to 2."

Ridiculous, especially as "log" can take two arguments as well.

LT

RichardJ
19-Tanzanite
(To:lturek)

WTF, why can't I quote your message when I am in "Advanced mode

Because it's not allowed

how can i switch back to "normal(?) mode"?

That's not allowed either

And it really seems to work for just a few selected functions.

As far as I know, only certain trig functions. I think there are even some built-in trig functions for which it doesn't work, but I don't recall which ones.

Please attach to the message your Mathcad worksheet. What version of Mathcad are you using?

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