expPdf function
Exponential density function
with non-zero support over the interval (0, inf)
.
Throws an exception of type ErrorOfType<InvalidFunctionParameter>
if mean <= 0
.
Implementation
double expPdf(num x, num mean) {
if (mean <= 0) {
throw ErrorOfType<InvalidFunctionParameter>(
message: 'Error in expPdf($x, $mean).',
invalidState: 'mean: $mean <= 0.',
expectedState: 'mean > 0',
);
}
return (x.isNegative) ? 0.0 : 1.0 / mean * math.exp(-x / mean);
}