normalCdf function
Normal cumulative probability density function.
Throws an error of type ErrorOfType<InvalidFunctionParameter>
if stdDev < 0
.
Implementation
double normalCdf(num x, num mean, num stdDev) {
if (stdDev <= 0.0) {
throw throw ErrorOfType<InvalidFunctionParameter>(
invalidState: 'stdDev: $stdDev <= 0.',
expectedState: 'stdDev > 0',
);
}
return 1 - 0.5 * erfc((x - mean) / (math.sqrt2 * stdDev));
}