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Re: double precision complex #s [message #4042 is a reply to message #3960]

Mon, 17 April 1995 00:00

thompson
Messages: 584
Registered: August 1991

Senior Member

agraps@netcom.com (Amara Graps) writes:

> psharer@eos.arc.nasa.gov (Peter J. Sharer) writes:

>> I am using the complex declaration for an array of complex numbers,
>> but am running into a problem with floating point overflows in a
>> polynomial calculation. Does anyone know of a way to create a complex
>> variable with double precision?

>> Thanks for your help,

>> Peter Sharer

> Peter,

> Try handling the real and imaginary parts this way (it's
> convoluted, but it works :) )

> IDL> a = [1,2,3]
> IDL> b = [4,5,6]
> IDL> c = complex(a,b)
> IDL> print, c
> ( 1.00000, 4.00000)( 2.00000, 5.00000)( 3.00000,
> 6.00000)

> To get double precision reals, use some of the rules of complex algebra,

> IDL> print, double(abs((c+conj(c))/2.0))
> 1.0000000 2.0000000 3.0000000

> To get double precision imaginary, use idl's imaginary function,

> IDL> print, double(imaginary(c))
> 4.0000000 5.0000000 6.0000000

> (There are more zeros than what's being printed here, but you get the
> idea.)

Uhhh, sorry to disappoint you, but simply taking a single precision number and
converting it to double precision does not mean that it has double precision
accuracy.

Fear not, IDL v4.0 will have a DCOMPLEX data type.

Bill Thompson

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[Message index]

		double precision complex #s By: psharer on Thu, 13 April 1995 00:00
		Re: double precision complex #s By: agraps on Mon, 17 April 1995 00:00
		Re: double precision complex #s By: thompson on Mon, 17 April 1995 00:00
		Re: double precision complex #s By: agraps on Sun, 16 April 1995 00:00

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