COMPLEX NUMBERS

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Using the TI-92 Plus with Complex Numbers

· Objectives: Demonstrate how the TI-92 Plus can be used to add, subtract, multiply and divide complex numbers.

§ Please note that i must be used in place of j to make entries in the TI-92 Plus.

Complex Operations in Rectangular Form

Let’s consider the four examples of complex algebra presented in Section 2. These operations can be easily entered in the calculator.

Examples:

1) Add 8+j5 and 2+j1;

2) Subtract 1 +j2 from 3+j4;

3) Multiply (5 + j3) by (2 – j4);

4) Divide (10+j5) by (2+j4).

In the following screen captures we illustrate the ease with which these operations can be carried out.

Complex Operations in Polar Form

The screen captures below present equally easy computations using the polar mode (i.e. phasor notation). First we need to select the following modes:

· Set floating point at 5 or less.

· Set angle to degree.

· Set complex to polar.

· Set exact/approximate to approximate.

We use the same four examples from above.

We use the same four examples from above. Note that in polar mode the same computations result in our phasor notation.

Mixing Forms – Rectangular and Phasor

In the following examples we use the TI-92 to carry out operations that use a mix of rectangular and phasor form; we also note that if the entry is typed in one mode the answer will be returned in the stored mode.

§ Suppose we store the phasor form in the mode setting.

Let’s consider: We note in the screen below that we can type in this combination of forms and, since we are in polar form, the answer will be returned.

§ Next we compute: with the stored phasor form

Once again, despite the combination of rectangular and phasor forms we can type in the computation as is and return the following answer:

§ What if we choose rectangular mode and type a computation solely in phasor form? We see in the screen below that the answer will be returned in rectangular form despite the phasor form of the entry.

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§ What if we are in polar mode and type a computation solely in rectangular form? We see in the screen below that the answer will be in the stored phasor form despite the rectangular form of the entry.

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Circuit Example

In the table below we have excerpts from a circuit problem at a site by Arizona State University. These pictures develop an analysis for the I-V relationship for a particular capacitor. In our last screen we present the TI-92 calculations that mirror the computations presented.

	In the screen below we carry out the computations to the left using the TI-92

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