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digerdiga

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10 years, 248 days
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These are questions asked by digerdiga

convert RootOf expression to actual anal...

digerdiga 380 Maple 15
rootof
June 27 2018
1 0

I have big expressions containing RootOf() which are however pretty simple.

For example something like

RootOf(x^2+1,x)

Is it possible to convert this later into the actual solution? e.g. +-*I ??

Function evaluation goes wrong, why?...

digerdiga 380 Maple 2015
int
June 25 2018
3 16

Hey and Thanks for your input.


 

> 

restart; f := ((1/2-I*t)^(-s)-(1/2+I*t)^(-s))/(2*I); fc := evalc(f); `assuming`([simplify(int(f, t = 0 .. infinity))], [s > 1]); `assuming`([simplify(int(fc, t = 0 .. infinity))], [s > 1])

-((1/2)*I)*((1/2-I*t)^(-s)-(1/2+I*t)^(-s))

  

exp(-(1/2)*s*ln(1/4+t^2))*sin(s*arctan(2*t))

  

2^(s-1)/(s-1)

  

(1/2)*4^s/(s-1)

 (1)
> 

``


 

Download function_evaluation_goes_wrong.mw

 

 

Am I doing something wrong?

Difference between type() and is()...

digerdiga 380 Maple 2018
type
June 23 2018
1 0

Hello,

I'm currently wondering about the "real" difference.

is() or type() can be used both for true/false checks. However when should what be used preferably?

For example I do not see what is better over the other when doing simple checks such as

is(2,'integer')

type(2,'integer')

 

Thanks for clarifying.

Cut of Errorfunction...

digerdiga 380 Maple 15
error-function
June 22 2018
1 1

I'm currently wondering about the cut I'm looking for in the following worksheet.

I evaluate it in 2 ways but get different answers. Any idea what the problem here is?

Thanks


 

> 

restart; dIs := sqrt(Pi/(I*s))*exp(I*s*t-I*s*omega0^2); Is1 := `assuming`([simplify(int(dIs, s))], [s > 0]); dIs := `assuming`([int(exp(-I*(omega^2+omega0^2-t)*s), omega = -infinity .. infinity)], [s > 0]); Is2 := int(%, s); plot3d(Im(eval(Is1, [t = x+I*y, s = 1, omega0 = 1])), x = -3 .. 3, y = -3 .. 3)

(-I*Pi/s)^(1/2)*exp(I*s*t-I*s*omega0^2)

  

(1/2-(1/2)*I)*Pi*2^(1/2)*erf(s^(1/2)*(I*(omega0^2-t))^(1/2))/(I*(omega0^2-t))^(1/2)

  

exp(I*s*t-I*s*omega0^2)*Pi^(1/2)/(I*s)^(1/2)

  

-I*Pi*erf((omega0^2-t)^(1/2)*(I*s)^(1/2))/(omega0^2-t)^(1/2)

  

 
> 

``


 

Download CutErrorFunction.mw

convert Ei1 to Ei...

digerdiga 380 Maple 2018
convert ei
June 19 2018
2 2

Is it possible to convert E1(x) to Ei(x) explicitly?

In particular I have this expression which is real, but imaginary numbers appear due to the definition of Ei1 for negative arguments.

(-exp(j*z)*Ei(1, j*z)+I*Pi*exp(-j*z)+exp(-j*z)*Ei(1, -j*z))/(2*j)

 

j>0,z>0

 

Thank you

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