Integrate w/o Bounds on TI-89: How to Change?

[jaejoon89]

When I use the integral feature, my TI-89 is giving a numerical answer even if I'm not selecting any bounds for integration (i.e., if I'm just taking the antiderivative). It's as if there's an implicit integral or something. How do I change this so I can just get a normal antiderivative?

For example, if the function is x (or whatever) and I do int[x,x] it gives 0.03125 instead of 1/2 x^2

 

[MATLABdude]

When I use the integral feature, my TI-89 is giving a numerical answer even if I'm not selecting any bounds for integration (i.e., if I'm just taking the antiderivative). It's as if there's an implicit integral or something. How do I change this so I can just get a normal antiderivative?

For example, if the function is x (or whatever) and I do int[x,x] it gives 0.03125 instead of 1/2 x^2

You probably have a value stored in 'x'. If you clear your variables (or, at least x, or use a different variable) you should get something symbolic. CAVEAT: I last used my TI-89 for something like what you're doing when TI-89s had only 1 MB of total memory.

 

[quicknote]

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I understand the frustration of encountering unexpected results while using a tool or software. In this case, it seems that the TI-89 is automatically performing a definite integral even when the user is not selecting any bounds for integration. This can be confusing and may not align with the user's desired outcome, which is to obtain a normal antiderivative.

To change this behavior, you can try adjusting the settings on your TI-89. First, go to the "Mode" menu and select "Function." Then, scroll down to the "Integration" section and make sure that the "Auto" option is unchecked. This will prevent the calculator from automatically performing a definite integral when no bounds are selected.

Additionally, you can also manually input the bounds for integration when using the integral feature. Instead of just selecting the function to integrate, you can type in the bounds in the format "int[f(x), x, a, b]" where a and b are the lower and upper bounds, respectively. This will ensure that the calculator performs a definite integral with the specified bounds.

I hope this helps you obtain the desired results when using the integral feature on your TI-89. As a scientist, it is important to understand and utilize the tools we have at our disposal, and to also be able to troubleshoot and adapt when unexpected results occur. Keep exploring and learning, and don't be afraid to reach out for help or further clarification when needed.