import * as math from 'mathjs';
export const volumeOfRevolution = (expression, start, end, steps = 1000) => {
if (steps <= 0) throw new Error('Steps must be positive');
if (steps > 100000) throw new Error('Steps too large for safety');
try {
const dx = (end - start) / steps;
let volume = 0;
const node = math.parse(expression);
for (let i = 0; i < steps; i++) {
const x = start + i * dx;
const scope = { x };
const y = node.evaluate(scope);
volume += Math.PI * y * y * dx;
}
return volume;
} catch (e) {
throw new Error(`Volume error: ${e.message}`);
}
};
export const compoundInterest = (principal, rate, time, compounds = 12) => {
if (principal < 0 || rate < 0 || time < 0 || compounds <= 0) {
throw new Error('Principal, rate, time must be non-negative and compounds must be positive');
}
return principal * Math.pow(1 + rate/compounds, compounds * time);
};
export const presentValue = (futureValue, rate, time) => {
if (time < 0) throw new Error('Time must be non-negative');
return futureValue / Math.pow(1 + rate, time);
};
export const npv = (cashFlows, rate) => {
return cashFlows.reduce((npv, cf, t) =>
npv + cf / Math.pow(1 + rate, t), 0);
};
