i41CX Known Issues


This version inadvertently introduced a conflict with iOS 5.1.1 devices.

This issue was resolved in Version 7.0.1.


Users that updated to iOS 8 have experienced a loss of settings, data, and the ability to use iTunes file sharing.

This issue was resolved in Version 6.3.


The iPad exclusive "Classic (No Stack)" skin does not work correctly. Until this issue is resolved, please use another skin. The skin can be set in the Settings app.

This issue was resolved in Version 5.5.2.

Note to iOS 5 users with in-app purchase upgrades

Tapping the "overlay" and "Load Data" buttons can cause the app to crash.

This issue was resolved in Version 4.9.

Note to iOS 4.2 users

Versions 4.7 and earlier exhibit some visual anomalies (e.g. "Calculator/Colors" toggle switch for users with the "Overlays Upgrade" or "i41CX+ Features Upgrade") and the "Upgrades" screen cannot be dismissed without force quitting the app when running under iOS 4.2.

These issues were resolved in Version 4.7.1.

Note to OS 3.0 users

Time synchronization does not work properly under OS 3.0. To use the clock and calendar functionality under OS 3.0, please set the global "Synchronize Time" and "Keep Time" options to OFF and ON, respectively, and set the time and date manually.

This issue was resolved in Version 3.0.

Note to 1st generation iPod touch users

Sounds, including the "New" and "Old" key click sounds, are only audible on the 1st generation iPod touch through the headphones. This is not a bug. It is a hardware limitation of the 1G iPod touch. To mitigate this limitation, versions 3.0 and later support a "System" key click sound option that uses the same sound as the Apple's built-in keyboard which is audible even on the 1st generation iPod without headphones. In addition, versions 1.1 and later support the option to enable a "glow" key press feedback effect.

VERSIONS 4.8-4.9.7 with either the "CAS Upgrade" or "i41CX+ Features Upgrade"

Files without a reserved file extension (i.e. CAS files) are not properly imported via iTunes file sharing. The recommended work-around for this issue is to use an iOS file system browser such as iExplorer to manually place the files into the CAS files directory of i41CX.

This issue was resolved in Version 4.9.8.

VERSION 4.8 with either the "CAS Upgrade" or the "i41CX+ Features Upgrade"

CAS plotting does not work in certain device configurations.

This issue was resolved in Version 4.8.1.


If the "Stack Display" setting is switched from OFF to ON in the global Settings application while the app is running, the stack display will not be displayed properly (an empty black status bar will be visible instead of the stack display). To resolve this issue, please toggle the "Stack Display" switch on the back view of the calculator from ON -> OFF -> ON. This will restore the stack display. Thereafter, toggling the in-app switch will work as expected so long as the switch in the global Settings application is not toggled while the app is running.

This issue was resolved in Version 4.6.


The app fails to launch if newly installed or deleted and reinstalled under OS 3.1.3 or earlier. The problem does not affect users updating from an earlier version regardless of the OS version. Unfortunately, there is no work-around for this issue.

This issue was resolved in Version 4.5.1.


  • The new I41CX-MATH module's ATAN2 function returns incorrect units when used in radians mode. The function returns the correct units in Degrees and Gradients modes. The following are three possible work-arounds for this issue.

    • Use ATAN2 in DEG or GRAD mode.

    • Multiply the result of ATAN2 by 180/π.

    • Use the following program in radians mode:

      01 LBL "ATAN2R"
      02 ATAN2
      03 180
      04 *
      05 PI
      06 /
      07 END

      If you have upgraded to i41CX+, you can enter this program by either tapping the above image in mobile Safari on your device or copy it on your device, launch i41CX, tap the "Load Data" button in the back view, tap the "Import from clipboard..." item to save it as a program on your device, and then tap the "Select" button to load it into the calculator memory.

    This issue was resolved in Version 3.4.

  • The location services functions time out. Unfortunately, there is no work around for this issue.

    This issue was resolved in Version 3.4.


i41CX may refuse to launch properly when updated from an earlier version. If you experience this problem, please update to Version 3.0.1.


If you are experiencing problems executing the newly introduced commands, please see FAQ entry C8.


  • Silent switch is not honored and background music stops when the application is launched.
  • Volume reverts back to the default level when the application is launched.
Please update to 1.0.1 or later to resolve these issues.