cdense_string.go

// Copyright (c) Harri Rautila, 2012

// This file is part of go.opt/matrix package. It is free software, distributed
// under the terms of GNU Lesser General Public License Version 3, or any later
// version. See the COPYING tile included in this archive.

package matrix

import (
	"errors"
	"fmt"
	"strconv"
	"strings"
)

// Convert matrix to row-major string representation.
func (A *ComplexMatrix) String() string {
	s := ""
	step := A.LeadingIndex()
	for i := 0; i < A.Rows(); i++ {
		if i > 0 {
			s += "\n"
		}
		s += "["
		for j := 0; j < A.Cols(); j++ {
			if j > 0 {
				s += " "
			}
			s += fmt.Sprintf("%v", A.elements[j*step+i])
		}
		s += "]"
	}
	return s
}

// Parse a matlab-style row-major matrix representation eg [a b c; d e f]
// and return a Matrix. Each element is pair of floats e.g.
// [(1.0+0i) (0.0+0i); (4-2i) (-1-2i)]
func ComplexParse(s string) (A *ComplexMatrix, err error) {
	var arrays [][]complex128
	start := strings.Index(s, "[")
	end := strings.LastIndex(s, "]")
	if start == -1 || end == -1 {
		err = errors.New("Unrecognized matrix string")
		return
	}
	rowStrings := strings.Split(s[start+1:end], ";")
	//nrows := len(rowStrings)
	ncols := 0
	for _, row := range rowStrings {
		rowElems := strings.Split(strings.Trim(row, ") "), ")")
		if ncols == 0 {
			ncols = len(rowElems)
		} else if ncols != len(rowElems) {
			err = ErrorDimensionMismatch
			return
		}
		row := []complex128{}
		for _, valString := range rowElems {
			var cval complex128
			valString = strings.Trim(valString, "( ")
			cval, err = parseComplex(valString)
			if err != nil {
				return
			}
			row = append(row, cval)
		}
		arrays = append(arrays, row)
	}
	A = ComplexMatrixFromTable(arrays, RowOrder)
	return
}

func parseComplex(s string) (v complex128, err error) {
	var re, im string
	var rval, ival float64

	v = complex(0, 0)
	str := strings.Trim(s, " ")
	ri := 0
	if str[0] == '-' || str[0] == '+' {
		ri += 1
	}
	if n := strings.Index(str[ri:], "+"); n != -1 {
		re = strings.Trim(str[:n+ri], " ")
		im = strings.Trim(str[n+ri:], " ")
	} else if n := strings.Index(str[ri:], "-"); n != -1 {
		re = strings.Trim(str[:n+ri], " ")
		im = strings.Trim(str[n+ri:], " ")
	} else {
		err = errors.New("invalid complex number")
		return
	}
	//fmt.Printf("re: '%s', im: '%s'\n", re, im)
	if im[len(im)-1] != 'i' {
		err = errors.New("invalid complex number, no imaginary part")
		return
	}
	rval, err = strconv.ParseFloat(re, 64)
	if err != nil {
		return
	}
	ival, err = strconv.ParseFloat(im[:len(im)-1], 64)
	if err != nil {
		return
	}
	v = complex(rval, ival)
	return
}

// Local Variables:
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