## org.apache.commons.math3.transform Class TransformUtils

```java.lang.Object org.apache.commons.math3.transform.TransformUtils
```

`public class TransformUtilsextends Object`

Useful functions for the implementation of various transforms.

Since:
3.0
Version:
\$Id: TransformUtils.java 1385310 2012-09-16 16:32:10Z tn \$

Method Summary
`static Complex[]` `createComplexArray(double[][] dataRI)`
Builds a new array of `Complex` from the specified two dimensional array of real and imaginary parts.
`static double[][]` `createRealImaginaryArray(Complex[] dataC)`
Builds a new two dimensional array of `double` filled with the real and imaginary parts of the specified `Complex` numbers.
`static int` `exactLog2(int n)`
Returns the base-2 logarithm of the specified `int`.
`static Complex[]` ```scaleArray(Complex[] f, double d)```
Multiply every component in the given complex array by the given real number.
`static double[]` ```scaleArray(double[] f, double d)```
Multiply every component in the given real array by the given real number.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Method Detail

### scaleArray

```public static double[] scaleArray(double[] f,
double d)```
Multiply every component in the given real array by the given real number. The change is made in place.

Parameters:
`f` - the real array to be scaled
`d` - the real scaling coefficient
Returns:
a reference to the scaled array

### scaleArray

```public static Complex[] scaleArray(Complex[] f,
double d)```
Multiply every component in the given complex array by the given real number. The change is made in place.

Parameters:
`f` - the complex array to be scaled
`d` - the real scaling coefficient
Returns:
a reference to the scaled array

### createRealImaginaryArray

`public static double[][] createRealImaginaryArray(Complex[] dataC)`
Builds a new two dimensional array of `double` filled with the real and imaginary parts of the specified `Complex` numbers. In the returned array `dataRI`, the data is laid out as follows
• `dataRI[i] = dataC[i].getReal()`,
• `dataRI[i] = dataC[i].getImaginary()`.

Parameters:
`dataC` - the array of `Complex` data to be transformed
Returns:
a two dimensional array filled with the real and imaginary parts of the specified complex input

### createComplexArray

```public static Complex[] createComplexArray(double[][] dataRI)
throws DimensionMismatchException```
Builds a new array of `Complex` from the specified two dimensional array of real and imaginary parts. In the returned array `dataC`, the data is laid out as follows
• `dataC[i].getReal() = dataRI[i]`,
• `dataC[i].getImaginary() = dataRI[i]`.

Parameters:
`dataRI` - the array of real and imaginary parts to be transformed
Returns:
an array of `Complex` with specified real and imaginary parts.
Throws:
`DimensionMismatchException` - if the number of rows of the specified array is not two, or the array is not rectangular

### exactLog2

```public static int exactLog2(int n)
throws MathIllegalArgumentException```
Returns the base-2 logarithm of the specified `int`. Throws an exception if `n` is not a power of two.

Parameters:
`n` - the `int` whose base-2 logarithm is to be evaluated
Returns:
the base-2 logarithm of `n`
Throws:
`MathIllegalArgumentException` - if `n` is not a power of two

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