Re: Mathmatical Question, Formula to multiply a number by smaller amounts?

On Wed, 28 Sep 2005 14:35:08 -0700, Zeusbwr <zeusbwr@xxxxxxxxx> wrote:

>double dMod = 1.05; // Modifier
>double dNumber = 1; // Number i wish to modify
>
>for( int i = 0; i < 5; i++ ){
>
>  dNumber = dNumber * dMod;
>  Console.Writeline( "Here is your {0} number: {1}, i, dNumber );
>  dMod = dMod * 0.95;
>
>}
>
>
>Now what i want to do is exactly that, each iteration i want to
>multiple a number by a ever smaller number. But the thing is, dMod
>cant change.
>
>Would it be possible to accomplish what is done with that loop,
>without modifying dMod?

Well, if I understand you correctly you just need to use powers
(which are essentially repeated multiplications, if the exponent
is an integer).

double dMod = 1.05; // Modifier
double dNumber = 1; // Number i wish to modify

for( int i = 0; i < 5; i++ )
{
  dNumber = dNumber * (dMod ^ (i + 1));
  Console.Writeline( "Here is your {0} number: {1}, i, dNumber );
}

So, you never modify dMod but you get the same results.
My C++ is rusty so you need to look up the
exact syntax for raising a number to an integer power.
If I recall correctly C(++) has no built-in support for raising
a number to a non-integer power but you don't need that.
(You can work around that by using exp and ln anyway.)

BTW, this is hugely off-topic. In the future you're better off
asking such things in any newsgroup that has "math" in its name
(e.g. comp.sci.math)

HTH

Sven

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