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Java library for reading and writing FITS files. FITS, the Flexible Image Transport System, is the format commonly used in the archiving and transport of astronomical data.
/*
* #%L
* nom.tam FITS library
* %%
* Copyright (C) 2004 - 2024 nom-tam-fits
* %%
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* of this software dedicate any and all copyright interest in the
* software to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and
* successors. We intend this dedication to be an overt act of
* relinquishment in perpetuity of all present and future rights to this
* software under copyright law.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
* #L%
*/
package nom.tam.util;
import java.util.StringTokenizer;
import java.util.logging.Logger;
import nom.tam.fits.FitsFactory;
import nom.tam.fits.LongValueException;
/**
*
* A no-frills complex value, for representing complex numbers in FITS headers. It is a non-mutable object that is
* created with a real and imaginary parts, which can be retrieved thereafter, and provides string formatting that is
* suited specifically for representation in FITS headers.
*
*
* Note that binary tables handle complex data differently, with elements of `float[2]` or `double[2]`.
*
*
* @author Attila Kovacs
*
* @since 1.16
*/
public class ComplexValue {
private static final Logger LOG = Logger.getLogger(ComplexValue.class.getName());
/** The complex zero **/
public static final ComplexValue ZERO = new ComplexValue(0.0, 0.0);
/** The complex unity along the real axis, or (1.0, 0.0) **/
public static final ComplexValue ONE = new ComplexValue(1.0, 0.0);
/** The unity along the imaginary axis i, or (0.0, 1.0) **/
public static final ComplexValue I = new ComplexValue(0.0, 1.0);
/** The real and imaginary parts */
private double re, im;
/**
* The minimum size string needed to represent a complex value with even just single digits for the real and
* imaginary parts.
*/
private static final int MIN_STRING_LENGTH = 5; // "(#,#)"
/**
* Private constructor
*/
private ComplexValue() {
}
/**
* Instantiates a new complex number value with the specified real and imaginary components.
*
* @param re the real part
* @param im thei maginary part
*/
public ComplexValue(double re, double im) {
this();
this.re = re;
this.im = im;
}
/**
* Returns the real part of this complex value.
*
* @return the real part
*
* @see #im()
*/
public final double re() {
return re;
}
/**
* Returns the imaginary part of this complex value.
*
* @return the imaginary part
*
* @see #re()
*/
public final double im() {
return im;
}
@Override
public int hashCode() {
return Double.hashCode(re()) ^ Double.hashCode(im());
}
@Override
public boolean equals(Object o) {
if (o == this) {
return true;
}
if (!(o instanceof ComplexValue)) {
return false;
}
ComplexValue z = (ComplexValue) o;
return z.re() == re() && z.im() == im();
}
/**
* Checks if the complex value is zero. That is, if both the real or imaginary parts are zero.
*
* @return trueif both the real or imaginary parts are zero. Otherwise false.
*/
public final boolean isZero() {
return re() == 0.0 && im() == 0.0;
}
/**
* Checks if the complex value is finite. That is, if neither the real or imaginary parts are NaN or Infinite.
*
* @return trueif neither the real or imaginary parts are NaN or Infinite. Otherwise
* false.
*/
public final boolean isFinite() {
return Double.isFinite(re()) && Double.isFinite(im());
}
@Override
public String toString() {
return "(" + re() + "," + im() + ")";
}
/**
* Converts this complex value to its string representation with up to the specified number of decimal places
* showing after the leading figure, for both the real and imaginary parts.
*
* @param decimals the maximum number of decimal places to show.
*
* @return the string representation with the specified precision, which may be used in a FITS header.
*
* @see FlexFormat
*/
public String toString(int decimals) {
FlexFormat f = new FlexFormat().setPrecision(decimals);
return "(" + f.format(re()) + "," + f.format(im()) + ")";
}
/**
*
* Instantiates a new complex number value from the string repressentation of it in a FITS header value. By default,
* it will parse complex numbers as a comma-separated pair of real values enclosed in a bracket, such as
* (1.0, -2.0), or standard real values, such as 123.456 or 123 (as real-only
* values). There can be any number of spaces around the brackets, number components or the comma.
*
*
* If {@link FitsFactory#setAllowHeaderRepairs(boolean)} is set true, the parsing becomes more
* tolerant, working around missing closing brackets, different number of comma-separated components, and missing
* empty components. So, for example (,-1,abc may be parsed assuming it was meant to be -i.
*
*
* @param text The FITS header value representing the complex number, in brackets with the real
* and imaginary pars separated by a comma. Additional spaces may surround the
* component parts.
*
* @throws IllegalArgumentException if the supplied string does not appear to be a FITS standard representation of a
* complex value.
*
* @see FitsFactory#setAllowHeaderRepairs(boolean)
*/
public ComplexValue(String text) throws IllegalArgumentException {
this();
// Allow the use of 'D' or 'd' to mark the exponent, instead of the standard 'E' or 'e'...
text = text.trim().toUpperCase().replace('D', 'E');
boolean hasOpeningBracket = text.charAt(0) == '(';
boolean hasClosingBracket = text.charAt(text.length() - 1) == ')';
if (!(hasOpeningBracket || hasClosingBracket)) {
// Use just the real value.
re = Double.parseDouble(text);
return;
}
if (!hasOpeningBracket || !hasClosingBracket) {
if (!FitsFactory.isAllowHeaderRepairs()) {
throw new IllegalArgumentException("Missing bracket around complex value: '" + text
+ "'\n\n --> Try FitsFactory.setAllowHeaderRepair(true).\n");
}
LOG.warning("Ignored missing bracket in '" + text + "'.");
}
int start = hasOpeningBracket ? 1 : 0;
int end = hasClosingBracket ? text.length() - 1 : text.length();
StringTokenizer tokens = new StringTokenizer(text.substring(start, end),
FitsFactory.isAllowHeaderRepairs() ? ",; \t" : ", ");
if (tokens.countTokens() != 2) {
if (!FitsFactory.isAllowHeaderRepairs()) {
throw new IllegalArgumentException(
"Invalid complex value: '" + text + "'\n\n --> Try FitsFactory.setAllowHeaderRepair(true).\n");
}
LOG.warning("Ignored wrong number of components (" + tokens.countTokens() + ") in '" + text + "'.");
}
if (tokens.hasMoreTokens()) {
re = Double.parseDouble(tokens.nextToken());
}
if (tokens.hasMoreTokens()) {
im = Double.parseDouble(tokens.nextToken());
}
}
/**
* Converts this comlex value to its string representation using up to the specified number of characters only. The
* precision may be reduced as necessary to ensure that the representation fits in the allotted space.
*
* @param maxLength the maximum length of the returned string representation
*
* @return the string representation, possibly with reduced precision to fit into the alotted
* space.
*
* @throws LongValueException if the space was too short to fit the value even with the minimal (1-digit) precision.
*/
public String toBoundedString(int maxLength) throws LongValueException {
if (maxLength < MIN_STRING_LENGTH) {
throw new LongValueException(maxLength, toString());
}
String s = toString();
if (s.length() <= maxLength) {
return s;
}
int decimals = FlexFormat.DOUBLE_DECIMALS;
s = toString(decimals);
while (s.length() > maxLength) {
// Assume both real and imaginary parts shorten the same amount...
decimals -= (s.length() - maxLength + 1) / 2;
if (decimals < 0) {
throw new LongValueException(maxLength, toString());
}
s = toString(decimals);
}
return s;
}
/**
* Converts this complex number to an array of 2.
*
* @return An array of 2 floating point values.
*
* @since 1.20
*/
Object toArray() {
return new double[] {re, im};
}
/**
* Single-precision complex values.
*
* @author Attila Kovacs
*
* @since 1.18
*/
public static final class Float extends ComplexValue {
/**
* Instantiates a new single-precision complex number value with the specified real and imaginary components.
*
* @param re the real part
* @param im thei maginary part
*
* @since 1.20
*/
public Float(float re, float im) {
super(re, im);
}
/**
*
* Instantiates a new single-precision complex number value from the string repressentation of it in a FITS
* header value. By default, it will parse complex numbers as a comma-separated pair of real values enclosed in
* a bracket, such as (1.0, -2.0), or standard real values, such as 123.456 or
* 123 (as real-only values). There can be any number of spaces around the brackets, number
* components or the comma.
*
*
* @param str the FITS string representation of the complex value
*
* @throws IllegalArgumentException if the supplied string does not appear to be a FITS standard representation
* of a complex value.
*
* @since 1.20
*/
public Float(String str) throws IllegalArgumentException {
super(str);
}
@Override
Object toArray() {
return new float[] {(float) re(), (float) im()};
}
}
}
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