net.objecthunter.exp4j.function.Functions Maven / Gradle / Ivy
/*
* Copyright 2014 Frank Asseg
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.objecthunter.exp4j.function;
/**
* Class representing the builtin functions available for use in expressions
*/
public class Functions {
private static final int INDEX_SIN = 0;
private static final int INDEX_COS = 1;
private static final int INDEX_TAN = 2;
private static final int INDEX_COT = 3;
private static final int INDEX_LOG = 4;
private static final int INDEX_LOG1P = 5;
private static final int INDEX_ABS = 6;
private static final int INDEX_ACOS = 7;
private static final int INDEX_ASIN = 8;
private static final int INDEX_ATAN = 9;
private static final int INDEX_CBRT = 10;
private static final int INDEX_CEIL = 11;
private static final int INDEX_FLOOR = 12;
private static final int INDEX_SINH = 13;
private static final int INDEX_SQRT = 14;
private static final int INDEX_TANH = 15;
private static final int INDEX_COSH = 16;
private static final int INDEX_POW = 17;
private static final int INDEX_EXP = 18;
private static final int INDEX_EXPM1 = 19;
private static final int INDEX_LOG10 = 20;
private static final int INDEX_LOG2 = 21;
private static final int INDEX_SGN = 22;
private static final Function[] builtinFunctions = new Function[23];
static {
builtinFunctions[INDEX_SIN] = new Function("sin") {
@Override
public double apply(double... args) {
return Math.sin(args[0]);
}
};
builtinFunctions[INDEX_COS] = new Function("cos") {
@Override
public double apply(double... args) {
return Math.cos(args[0]);
}
};
builtinFunctions[INDEX_TAN] = new Function("tan") {
@Override
public double apply(double... args) {
return Math.tan(args[0]);
}
};
builtinFunctions[INDEX_COT] = new Function("cot") {
@Override
public double apply(double... args) {
double tan = Math.tan(args[0]);
if (tan == 0d) {
throw new ArithmeticException("Division by zero in cotangent!");
}
return 1d/Math.tan(args[0]);
}
};
builtinFunctions[INDEX_LOG] = new Function("log") {
@Override
public double apply(double... args) {
return Math.log(args[0]);
}
};
builtinFunctions[INDEX_LOG2] = new Function("log2") {
@Override
public double apply(double... args) {
return Math.log(args[0]) / Math.log(2d);
}
};
builtinFunctions[INDEX_LOG10] = new Function("log10") {
@Override
public double apply(double... args) {
return Math.log10(args[0]);
}
};
builtinFunctions[INDEX_LOG1P] = new Function("log1p") {
@Override
public double apply(double... args) {
return Math.log1p(args[0]);
}
};
builtinFunctions[INDEX_ABS] = new Function("abs") {
@Override
public double apply(double... args) {
return Math.abs(args[0]);
}
};
builtinFunctions[INDEX_ACOS] = new Function("acos") {
@Override
public double apply(double... args) {
return Math.acos(args[0]);
}
};
builtinFunctions[INDEX_ASIN] = new Function("asin") {
@Override
public double apply(double... args) {
return Math.asin(args[0]);
}
};
builtinFunctions[INDEX_ATAN] = new Function("atan") {
@Override
public double apply(double... args) {
return Math.atan(args[0]);
}
};
builtinFunctions[INDEX_CBRT] = new Function("cbrt") {
@Override
public double apply(double... args) {
return Math.cbrt(args[0]);
}
};
builtinFunctions[INDEX_FLOOR] = new Function("floor") {
@Override
public double apply(double... args) {
return Math.floor(args[0]);
}
};
builtinFunctions[INDEX_SINH] = new Function("sinh") {
@Override
public double apply(double... args) {
return Math.sinh(args[0]);
}
};
builtinFunctions[INDEX_SQRT] = new Function("sqrt") {
@Override
public double apply(double... args) {
return Math.sqrt(args[0]);
}
};
builtinFunctions[INDEX_TANH] = new Function("tanh") {
@Override
public double apply(double... args) {
return Math.tanh(args[0]);
}
};
builtinFunctions[INDEX_COSH] = new Function("cosh") {
@Override
public double apply(double... args) {
return Math.cosh(args[0]);
}
};
builtinFunctions[INDEX_CEIL] = new Function("ceil") {
@Override
public double apply(double... args) {
return Math.ceil(args[0]);
}
};
builtinFunctions[INDEX_POW] = new Function("pow", 2) {
@Override
public double apply(double... args) {
return Math.pow(args[0], args[1]);
}
};
builtinFunctions[INDEX_EXP] = new Function("exp", 1) {
@Override
public double apply(double... args) {
return Math.exp(args[0]);
}
};
builtinFunctions[INDEX_EXPM1] = new Function("expm1", 1) {
@Override
public double apply(double... args) {
return Math.expm1(args[0]);
}
};
builtinFunctions[INDEX_SGN] = new Function("signum", 1) {
@Override
public double apply(double... args) {
if (args[0] > 0) {
return 1;
} else if (args[0] < 0) {
return -1;
} else {
return 0;
}
}
};
}
/**
* Get the builtin function for a given name
* @param name te name of the function
* @return a Function instance
*/
public static Function getBuiltinFunction(final String name) {
if (name.equals("sin")) {
return builtinFunctions[INDEX_SIN];
} else if (name.equals("cos")) {
return builtinFunctions[INDEX_COS];
} else if (name.equals("tan")) {
return builtinFunctions[INDEX_TAN];
} else if (name.equals("cot")) {
return builtinFunctions[INDEX_COT];
} else if (name.equals("asin")) {
return builtinFunctions[INDEX_ASIN];
} else if (name.equals("acos")) {
return builtinFunctions[INDEX_ACOS];
} else if (name.equals("atan")) {
return builtinFunctions[INDEX_ATAN];
} else if (name.equals("sinh")) {
return builtinFunctions[INDEX_SINH];
} else if (name.equals("cosh")) {
return builtinFunctions[INDEX_COSH];
} else if (name.equals("tanh")) {
return builtinFunctions[INDEX_TANH];
} else if (name.equals("abs")) {
return builtinFunctions[INDEX_ABS];
} else if (name.equals("log")) {
return builtinFunctions[INDEX_LOG];
} else if (name.equals("log10")) {
return builtinFunctions[INDEX_LOG10];
} else if (name.equals("log2")) {
return builtinFunctions[INDEX_LOG2];
} else if (name.equals("log1p")) {
return builtinFunctions[INDEX_LOG1P];
} else if (name.equals("ceil")) {
return builtinFunctions[INDEX_CEIL];
} else if (name.equals("floor")) {
return builtinFunctions[INDEX_FLOOR];
} else if (name.equals("sqrt")) {
return builtinFunctions[INDEX_SQRT];
} else if (name.equals("cbrt")) {
return builtinFunctions[INDEX_CBRT];
} else if (name.equals("pow")) {
return builtinFunctions[INDEX_POW];
} else if (name.equals("exp")) {
return builtinFunctions[INDEX_EXP];
} else if (name.equals("expm1")) {
return builtinFunctions[INDEX_EXPM1];
} else if (name.equals("signum")) {
return builtinFunctions[INDEX_SGN];
} else {
return null;
}
}
}
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