How to stop Mathematica from giving numerical answer?

Question

I am very new to Mathematica. Everything is a nightmare to me. I am trying to calculate a product

Product[((1 - 0.9 z^-1 Power[E, -I k (11 \[Pi])/50]) (1 - 
 0.9 z^-1 Power[E, I k (11 \[Pi])/50])), {k, 1, 4}]

but Mathematica answers on the form

(1 - (0.6934619184982104 + 0.5736815907738206*I)/z)*
(1 - (0.6934619184982104 - 0.5736815907738206*I)/z)*
(1 - (0.16864318312715226 + 0.8840585256558198*I)/z)*
(1 - (0.16864318312715226 - 0.8840585256558198*I)/z)*
(1 + (0.4335783066915439 - 0.7886760120394771*I)/z)*
(1 + (0.4335783066915439 + 0.7886760120394771*I)/z)*
(1 + (0.8367988372994263 - 0.3313120974162103*I)/z)*
(1 + (0.8367988372994263 + 0.3313120974162103*I)/z)

whereas I would like to retain the exact exponential form instead of evaluating the expression numerically.

Thanks

@b.gatessucks Please write this as an answer and i will pick that as the answer. It worked! Big kiss on your forehead! — mickey, Dec 03 '13 at 20:04
Nothing wrong in answering your own question ! Give it a go. — b.gatessucks, Dec 03 '13 at 20:05

score 3 · Answer 1 · answered Dec 03 '13 at 20:17

3

It turns out that I myself was to blame since i had entered a numerical value. I should have put 9/10 instead of 0.9. When i changed it everything worked as expected!

The answer came from this comment:

You can use 9/10 or Rationalize[0.9] in place of 0.9. –  b.gatessucks

Thanks b.gatessucks, for the answer and the rep of answering my own question with your answer!

answered Dec 03 '13 at 20:17

mickey

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Note that in addition to the symbolic evaluation (using `9/10`) and the machine precision evaluation (using `0.9`) you can also activate [arbitrary precision](http://mathematica.stackexchange.com/a/3153/121) using e.g. ``0.9`30`` or `SetPrecision`/`SetAccuracy`. – Mr.Wizard Dec 15 '13 at 07:39

How to stop Mathematica from giving numerical answer?

1 Answers1