Without Using Pow Function In C

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Topic: Without Using Pow Function In C (Read 379 views)

Sherlin

Without Using Pow Function In C

« on: June 02, 2006, 04:52 AM »

Hi,

Can anyone help me to find the power of a number without using pow function in C. For eg., 2.5 raised to the power of 1.5.

Thanks.

Seun (m)

Re: Without Using Pow Function In C

« #1 on: June 02, 2006, 11:17 AM »

If it's an integer, I can help. But raising to the power of a floating point number? No idea!

c0dec (m)

Re: Without Using Pow Function In C

« #2 on: June 05, 2006, 08:46 AM »

for integers this should work:

Code:

int powi(int number, int exponent)
{
int i, product = 1;
for (i = 0; i < exponent; i++)
product *= number;

return product;
}

for floats, well i don't have time now to test it but i guess this should work:

Code:

double powf(float base, float exponent)
{
return exp(log(base) * exponent);
}

c0dec (m)

Re: Without Using Pow Function In C

« #3 on: June 05, 2006, 09:05 AM »

oh and if log(x) doesn't produce what u need, try log10(x).

Seun (m)

Re: Without Using Pow Function In C

« #4 on: June 05, 2006, 10:44 AM »

Thanks for sharing. Didn't feel that the use of the log finction would be allowed. Undecided

c0dec (m)

Re: Without Using Pow Function In C

« #5 on: June 05, 2006, 05:46 PM »

no problem. i didn't think log was allowed but i didnt see any other way of solving it except some taylor series expansion wahala.

pfowighz (m)

Re: Without Using Pow Function In C

« #6 on: June 09, 2006, 04:08 PM »

Quote

double powf(float base, float exponent)

Shudnt that be

float powf(float base, float exponent)

The return val cud be a floating point stuff now, can't it?

c0dec (m)

Re: Without Using Pow Function In C

« #7 on: June 09, 2006, 07:19 PM »

exp() returns a double.

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