Printing complex numbers with fprintf

Chris Severns

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Apr 25, 2005, 6:06:25 PM4/25/05

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I'm attempting to print a complex number (x+j*y) using fprintf. I'm
only getting the real componet when I use %f or %g (e.g.
fprintf('%1.4g \n', z).

Any ideas?

perhaps I need to print the real and then the imginary in two parts:
fprintf('%1.4g %1.4g \n', real(z), imag(z))

but is there a way to avoid this?

Thanks.

Murphy O'Brien

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Apr 25, 2005, 7:26:53 PM4/25/05

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Not that I know of. I would probably do this though.

fprintf('%5.4g + j%5.4g\n', real(z), imag(z))

Murphy

Dan Hensley

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Apr 25, 2005, 7:33:16 PM4/25/05

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On Mon, 25 Apr 2005 19:26:53 -0400, Murphy O'Brien wrote:

> Not that I know of. I would probably do this though.
>
> fprintf('%5.4g + j%5.4g\n', real(z), imag(z))

If z is a vector, do this:

fprintf('%5.4g + j%5.4g\n', [real(z) imag(z)].');

Dan

Abas

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Apr 27, 2005, 1:01:52 AM4/27/05

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Hi,
You can use 'disp' function instead of 'fprintf'.
'disp' display a complex number, but 'fprintf' show only the real
part.

James

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May 29, 2013, 5:46:11 AM5/29/13

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"Chris Severns" <christophe...@boeing.com> wrote in message <ef03f...@webx.raydaftYaTP>...

Hi Chris

This is 8 years late but perhaps still of use to some people!

Try

fprintf( '%s \n' , num2str(z) )

J

Rick

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Nov 28, 2014, 1:54:12 PM11/28/14

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"James " <jc...@ic.ac.uk> wrote in message <ko4ip3$f00$1...@newscl01ah.mathworks.com>...

This solution works perfectly. Thanks for contributing this!

Karun

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Jan 8, 2015, 4:17:11 PM1/8/15

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"James " <jc...@ic.ac.uk> wrote in message <ko4ip3$f00$1...@newscl01ah.mathworks.com>...

That worked perfectly my man! Have a 2015 thank you

Honigmelone

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Mar 21, 2016, 10:56:10 AM3/21/16

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> > I'm attempting to print a complex number (x+j*y) using fprintf. I'm
> > only getting the real componet when I use %f or %g (e.g.
> > fprintf('%1.4g \n', z).
> >
> > Any ideas?
> >
> > perhaps I need to print the real and then the imginary in two parts:
> > fprintf('%1.4g %1.4g \n', real(z), imag(z))
> >
> > but is there a way to avoid this?
> >
> > Thanks.
>
> Hi Chris
>
> This is 8 years late but perhaps still of use to some people!
>
> Try
>
> fprintf( '%s \n' , num2str(z) )
>
> J

Hey, when I try this with row vectors containing complex numbers I get a strange result:
fprintf('%s\n',num2str([sqrt(-2);sqrt(-2)]))
00++11..44114422ii
whereas
num2str([sqrt(-2);sqrt(-2)])
ans =
0+1.4142i
0+1.4142i

Any Idea what I've done wrong? Thanks!

Bruno Luong

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Mar 21, 2016, 11:16:09 AM3/21/16

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num2str returns an array, and the characters are aranged columnwise. If you don't know what I'm talking about just apply blindly this:

>> c=cellstr(num2str([sqrt(-2);sqrt(-2)]))

c =

'0+1.4142i'
'0+1.4142i'

>> fprintf('%s\n',c{:})
0+1.4142i
0+1.4142i

Steven Lord

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Mar 22, 2016, 9:35:33 AM3/22/16

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"Honigmelone" <Math...@alshu.de> wrote in message
news:ncp224$hcu$1...@newscl01ah.mathworks.com...

Elements in matrices are stored in column major order.

A = reshape(1:16, 4, 4)

Note how the elements of A increase down each column first, then once the
column is full the next element starts at the top of the next column? The
same holds for character matrices:

B = reshape('a':'z', 2, 13)

Some other languages are row major:

C = reshape('a':'z', 13, 2).'

https://en.wikipedia.org/wiki/Row-major_order

When you call NUM2STR on a column vector, the result will be a char matrix
with a number of rows equal to the number of rows in the column vector.

D = num2str(sqrt([-2; -2]))
size(D)
class(D)

When FPRINTF prints D, it walks that matrix in column order.

fprintf('%s', D)

You can see this a little easier with a different vector, where the two rows
aren't identical:

E = num2str(sqrt([-2; -7]))
F = sprintf('%s', E)
G = F(1:2:end)
H = F(2:2:end)

G matches the first row in E while H matches the second.

--
Steve Lord
sl...@mathworks.com
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