How can I calculate logarithm in Java ME? There isn't any method in Java ME's Math
class for it, but it is available in the Java SE's开发者_C百科 Math
class.
It is suggested how it can be done here.
Here's a solution from that site:
private static double pow(double base, int exp){
if(exp == 0) return 1;
double res = base;
for(;exp > 1; --exp)
res *= base;
return res;
}
public static double log(double x) {
long l = Double.doubleToLongBits(x);
long exp = ((0x7ff0000000000000L & l) >> 52) - 1023;
double man = (0x000fffffffffffffL & l) / (double)0x10000000000000L + 1.0;
double lnm = 0.0;
double a = (man - 1) / (man + 1);
for( int n = 1; n < 7; n += 2) {
lnm += pow(a, n) / n;
}
return 2 * lnm + exp * 0.69314718055994530941723212145818;
}
I have used Nikolay Klimchuk's "Float11" class for floating-point calculations in Java ME. The original link seems broken, but it's available here.
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