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Changed implementations to handle the case where rate=0. Updated javadocs.

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git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/trunk@353722 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Amol S. Deshmukh 2005-06-22 20:42:40 +00:00
parent b0decdc046
commit e0fbd5d76d
2 changed files with 131 additions and 23 deletions
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62
src/scratchpad/src/org/apache/poi/hssf/record/formula/functions/FinanceFunction.java Normal file
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@ -0,0 +1,62 @@
/*
* Created on Jun 20, 2005
*
*/
package org.apache.poi.hssf.record.formula.functions;
import org.apache.poi.hssf.record.formula.eval.BoolEval;
import org.apache.poi.hssf.record.formula.eval.ErrorEval;
import org.apache.poi.hssf.record.formula.eval.Eval;
import org.apache.poi.hssf.record.formula.eval.NumericValueEval;
import org.apache.poi.hssf.record.formula.eval.ValueEval;
import org.apache.poi.hssf.record.formula.eval.ValueEvalToNumericXlator;
/**
* @author Amol S. Deshmukh < amolweb at ya hoo dot com >
* Super class for all Evals for financial function evaluation.
*
*/
public abstract class FinanceFunction extends NumericFunction {
private static final ValueEvalToNumericXlator DEFAULT_NUM_XLATOR =
new ValueEvalToNumericXlator((short) (0
| ValueEvalToNumericXlator.BOOL_IS_PARSED
| ValueEvalToNumericXlator.REF_BOOL_IS_PARSED
| ValueEvalToNumericXlator.EVALUATED_REF_BOOL_IS_PARSED
| ValueEvalToNumericXlator.STRING_IS_PARSED
| ValueEvalToNumericXlator.REF_STRING_IS_PARSED
| ValueEvalToNumericXlator.EVALUATED_REF_STRING_IS_PARSED
| ValueEvalToNumericXlator.BLANK_IS_PARSED
| ValueEvalToNumericXlator.REF_BLANK_IS_PARSED
| ValueEvalToNumericXlator.EVALUATED_REF_BLANK_IS_PARSED
//| ValueEvalToNumericXlator.REF_STRING_TO_BOOL_IS_PARSED
//| ValueEvalToNumericXlator.STRING_IS_INVALID_VALUE
//| ValueEvalToNumericXlator.REF_STRING_IS_INVALID_VALUE
));
/**
* this is the default impl of the factory(ish) method getXlator.
* Subclasses can override this method
* if they desire to return a different ValueEvalToNumericXlator instance
* than the default.
*/
protected ValueEvalToNumericXlator getXlator() {
return DEFAULT_NUM_XLATOR;
}
protected ValueEval singleOperandNumericAsBoolean(Eval eval, int srcRow, short srcCol) {
ValueEval retval = null;
retval = singleOperandEvaluate(eval, srcRow, srcCol);
if (retval instanceof NumericValueEval) {
NumericValueEval nve = (NumericValueEval) retval;
retval = (nve.getNumberValue() == 0)
? BoolEval.FALSE
: BoolEval.TRUE;
}
else {
retval = ErrorEval.VALUE_INVALID;
}
return retval;
}
}

72
src/scratchpad/src/org/apache/poi/hssf/record/formula/functions/FinanceLib.java
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@ -24,9 +24,26 @@ package org.apache.poi.hssf.record.formula.functions;
* <ol>
* <li>GNU Emacs Calc 2.02 Manual: http://theory.uwinnipeg.ca/gnu/calc/calc_203.html</li>
* <li>Yahoo Financial Glossary: http://biz.yahoo.com/f/g/nn.html#y</li>
* <li>MS Excel function reference: http://office.microsoft.com/en-us/assistance/CH062528251033.aspx</li>
* </ol>
* <h3>Implementation Notes:</h3>
* Symbols used in the formulae that follow:<br/>
* <ul>
* <li>p: present value</li>
* <li>f: future value</li>
* <li>n: number of periods</li>
* <li>y: payment (in each period)</li>
* <li>r: rate</li>
* <li>^: the power operator (NOT the java bitwise XOR operator!)</li>
* </ul>
* [From MS Excel function reference] Following are some of the key formulas
* that are used in this implementation:
* <pre>
* p(1+r)^n + y(1+rt)((1+r)^n-1)/r + f=0 ...{when r!=0}
* ny + p + f=0 ...{when r=0}
* </pre>
*/
public class FinanceLib {
public final class FinanceLib {
// constants for default values
@ -46,12 +63,19 @@ public class FinanceLib {
* @param t type (true=pmt at end of period, false=pmt at begining of period)
* @return
*/
public static double fv(double r, int n, double y, double p, boolean t) {
public static double fv(double r, double n, double y, double p, boolean t) {
double retval = 0;
if (r == 0) {
retval = -1*(p+(n*y));
}
else {
double r1 = r + 1;
return ((1-Math.pow(r1, n)) * (t ? r1 : 1) * y ) / r
retval =((1-Math.pow(r1, n)) * (t ? r1 : 1) * y ) / r
-
p*Math.pow(r1, n);
}
return retval;
}
/**
* Present value of an amount given the number of future payments, rate, amount
@ -65,12 +89,19 @@ public class FinanceLib {
* @param t
* @return
*/
public static double pv(double r, int n, double y, double f, boolean t) {
public static double pv(double r, double n, double y, double f, boolean t) {
double retval = 0;
if (r == 0) {
retval = -1*((n*y)+f);
}
else {
double r1 = r + 1;
return (( ( 1 - Math.pow(r1, n) ) / r ) * (t ? r1 : 1) * y - f)
retval =(( ( 1 - Math.pow(r1, n) ) / r ) * (t ? r1 : 1) * y - f)
/
Math.pow(r1, n);
}
return retval;
}
/**
* calculates the Net Present Value of a principal amount
@ -102,12 +133,19 @@ public class FinanceLib {
* @param t
* @return
*/
public static double pmt(double r, int n, double p, double f, boolean t) {
public static double pmt(double r, double n, double p, double f, boolean t) {
double retval = 0;
if (r == 0) {
retval = -1*(f+p)/n;
}
else {
double r1 = r + 1;
return ( f + p * Math.pow(r1, n) ) * r
retval = ( f + p * Math.pow(r1, n) ) * r
/
((t ? r1 : 1) * (1 - Math.pow(r1, n)));
}
return retval;
}
/**
*
@ -118,15 +156,23 @@ public class FinanceLib {
* @param t
* @return
*/
public static int nper(double r, double y, double p, double f, boolean t) {
public static double nper(double r, double y, double p, double f, boolean t) {
double retval = 0;
if (r == 0) {
retval = -1 * (f + p) / y;
} else {
double r1 = r + 1;
double ryr = (t ? r1 : 1) * y / r;
double a1 = ((ryr-f) < 0) ? Math.log(f-ryr) : Math.log(ryr-f);
double a2 = ((ryr-f) < 0) ? Math.log(-p-ryr) : Math.log(p+ryr);
double a1 = ((ryr - f) < 0)
? Math.log(f - ryr)
: Math.log(ryr - f);
double a2 = ((ryr - f) < 0)
? Math.log(-p - ryr)
: Math.log(p + ryr);
double a3 = Math.log(r1);
double dval = ( a1 - a2 ) / a3;
return (int) Math.round(dval);
retval = (a1 - a2) / a3;
}
return retval;
}