Control System Calc vs Calcanto

Control System Calc (ControlCalc) is an engineering tool for control engineers, R&D staff and students. Enter a transfer function to perform PID tuning, frequency-domain analysis and time-domain simulation — turning textbook control theory into a pocket tool you can use anywhere. All calculations run locally on your device, no internet required. KEY FEATURES ■ PID Tuning Five classic tuning methods built in: Ziegler-Nichols open-loop step, Cohen-Coon, Ziegler-Nichols closed-loop ultimate, plus IMC-Lambda and AMIGO. Each method includes guidance on when to use it. ■ Closed-Loop Step Simulation Simulate the closed-loop step response with an FOPDT model and a PID controller with derivative filtering. View the control effort u(t) to spot actuator saturation, and fine-tune parameters by hand. ■ Bode Plot & Stability Margins Draw magnitude and phase curves on a log scale, with automatic 0 dB / −180° reference lines, gain margin, phase margin and crossover frequencies — stability at a glance. ■ Step Response & Performance Metrics RK4 time-domain simulation that automatically computes overshoot, rise time and settling time. ■ Second-Order Designer Back-solve system parameters from overshoot Mp / settling time ts, or from damping ratio ζ / natural frequency ωn, then push them to the step-response page in one tap. ■ Root Locus & Nyquist (Pro) Root-locus branch tracing with the imaginary-axis stability boundary, an equal-aspect Nyquist plot with unit circle, plus pole/stability analysis for deeper insight. THOUGHTFUL DETAILS • Built-in library of classic example models — tap to load and go • Draggable readouts on time-domain curves (live t / y display) • Numeric keyboard with a Done button; input parameters persist automatically • Simplified Chinese / English / German / Japanese, switchable in-app instantly PRO UPGRADE (one-time purchase) • Removes all ads • Unlocks IMC-Lambda / AMIGO tuning methods • Unlocks Nyquist plot, root locus and pole/stability analysis • Unlocks CSV data export Buy once, keep forever. Family Sharing supported. WHO IS IT FOR Control, electrical, mechatronics and process engineers, R&D and commissioning staff, students taking control-theory courses, and anyone who needs to quickly validate a control-system design. DISCLAIMER All results are provided for engineering reference only. Real-world system design and commissioning should combine field conditions with professional judgment. Have feedback or questions? Contact us from the Settings page.

Calcanto is a calculator that says its results out loud, changes its look, and gets the arithmetic right. 0.1 + 0.2 = 0.3 The basic engine works in Decimal rather than binary floating point, so that sum comes out as 0.3 and not 0.30000000000000004. Results carry 15 significant digits, rounded half-up. IT SPEAKS, IN TWO LANGUAGES A female and a male voice. Each language reads a number the way that language does: 120 is "one hundred twenty" in English and 一百二十 in Chinese, never a digit-by-digit spell-out. Keys are announced as you press them and the whole result is read at the end. Every clip ships inside the app and is stitched together on the device, so the readout works in Airplane mode with nothing sent anywhere. Press = and a string is plucked. Each theme has its own pluck, and it is a separate switch from the spoken readout — turn narration off and the pluck is still there. FIVE THEMES, SWITCHED WHILE YOU WATCH Onyx, Seaglass, Bubblegum, Titanium and Neon Noir. All five are in the app. None is behind a purchase and there is no theme store to visit. Changing the theme changes the sound of = with it. THREE MODES Basic — four operations, percent, sign, decimal point, backspace, clear. Multiplication binds before addition, and pressing = again repeats the last operation. Scientific — sin, cos, tan and their inverses, the hyperbolic set and theirs, ln, log₁₀, x^y and the y-th root, x², x³, √, ³√, x!, 1/x, e^x, 10^x, EE, Rand, π, e, parentheses, mc / m+ / m− / mr, 2nd, and a Rad / Deg switch. Convert — five categories. Currency covers nine: USD, CNY, EUR, JPY, GBP, HKD, KRW, AUD and CAD, on live rates labelled with when they were fetched. Length, weight, temperature and area never need a network at all. HISTORY YOU CAN PUT BACK Expression, result, time and mode are all kept. Tap an entry and it drops straight back into the input. Delete one, or clear the lot. ACCESSIBILITY, NOT AN ACCESSIBILITY MODE Every key carries a VoiceOver label written to be heard rather than read: "+" is announced as "plus", and a toggled key says which way it is currently set. Dynamic Type scales the display and the keypad as far as a fixed grid can take them, while Settings, History and the sheets keep the full range. When a key fills with its theme's accent colour, the label colour is re-picked at runtime so it stays readable. ENGLISH AND CHINESE, SWITCHED INSIDE THE APP Settings → Language applies at once, with no restart. It is independent of the system language, and independent of which language the readout speaks — an English interface reading its results in Chinese is a legitimate combination. WHAT IT DOES NOT DO No account, no sign-in, no ads, no subscription, no analytics or advertising SDK — there is no third-party SDK in it at all. History, theme and voice settings stay on your device and sync nowhere. The app makes exactly one kind of network request, for exchange rates; never open Convert and it never goes online. Free, with no in-app purchase. iOS and iPadOS 17 or later, macOS 14 or later — one download covers all three.