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Landon Curt Noll
242
help/operator
242
help/operator
@@ -1,7 +1,7 @@
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operators
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The operators are similar to C, but there are some differences in
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the associativity and precedence rules for some operators. In
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the associativity and precedence rules for some operators. In
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addition, there are several operators not in C, and some C
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operators are missing. A more detailed discussion of situations
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that may be unexpected for the C programmer may be found in
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@@ -18,35 +18,35 @@ operators
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skipping of terms may occur for ||, && and ? : . For example,
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an expression of the form:
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A * B + C * D
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A * B + C * D
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is evaluated in the following order:
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A
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B
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A * B
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C
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D
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C * D
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A * B + C * D
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A
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B
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A * B
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C
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D
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C * D
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A * B + C * D
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This order of evaluation is significant if evaluation of a
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term changes a variable on which a later term depends. For example:
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x++ * x++ + x++ * x++
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x++ * x++ + x++ * x++
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returns the value of:
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x * (x + 1) + (x + 2) * (x + 3)
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x * (x + 1) + (x + 2) * (x + 3)
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and increments x as if by x += 4. Similarly, for functions f, g,
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the expression:
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f(x++, x++) + g(x++)
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f(x++, x++) + g(x++)
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evaluates to:
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f(x, x + 1) + g(x + 2)
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f(x, x + 1) + g(x + 2)
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and increments x three times.
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@@ -56,153 +56,153 @@ operators
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it returns x + 1 and increments x twice.
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, Comma operator.
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a, b returns the value of b.
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For situations in which a comma is used for another purpose
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(function arguments, array indexing, and the print statement),
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parenthesis must be used around the comma operator expression.
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E.g., if A is a matrix, A[(a, b), c] evaluates a, b, and c, and
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returns the value of A[b, c].
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, Comma operator.
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a, b returns the value of b.
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For situations in which a comma is used for another purpose
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(function arguments, array indexing, and the print statement),
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parenthesis must be used around the comma operator expression.
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E.g., if A is a matrix, A[(a, b), c] evaluates a, b, and c, and
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returns the value of A[b, c].
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+= -= *= /= %= //= &= |= <<= >>= ^= **=
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Operator-with-assignments.
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These associate from left to right, e.g. a += b *= c has the
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effect of a = (a + b) * c, where only a is required to be an
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lvalue. For the effect of b *= c; a += b; when both a and b
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are lvalues, use a += (b *= c).
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+= -= *= /= %= //= &= |= <<= >>= ^= **=
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Operator-with-assignments.
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These associate from left to right, e.g. a += b *= c has the
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effect of a = (a + b) * c, where only a is required to be an
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lvalue. For the effect of b *= c; a += b; when both a and b
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are lvalues, use a += (b *= c).
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= Assignment.
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As in C, this, when repeated, this associates from right to left,
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e.g. a = b = c has the effect of a = (b = c). Here both a and b
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are to be lvalues.
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= Assignment.
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As in C, this, when repeated, this associates from right to left,
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e.g. a = b = c has the effect of a = (b = c). Here both a and b
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are to be lvalues.
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? : Conditional value.
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a ? b : c returns b if a tests as true (i.e. nonzero if
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a is a number), c otherwise. Thus it is equivalent to:
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if (a) return b; else return c;.
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All that is required of the arguments in this function
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is that the "is-it-true?" test is meaningful for a.
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As in C, this operator associates from right to left,
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i.e. a ? b : c ? d : e is evaluated as a ? b : (c ? d : e).
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a ? b : c returns b if a tests as true (i.e. nonzero if
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a is a number), c otherwise. Thus it is equivalent to:
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if (a) return b; else return c;.
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All that is required of the arguments in this function
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is that the "is-it-true?" test is meaningful for a.
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As in C, this operator associates from right to left,
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i.e. a ? b : c ? d : e is evaluated as a ? b : (c ? d : e).
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|| Logical OR.
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Unlike C, the result for a || b is one of the operands
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a, b rather than one of the numbers 0 and 1.
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a || b is equivalent to a ? a : b, i.e. if a tests as
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true, a is returned, otherwise b. The effect in a
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test like "if (a || b) ... " is the same as in C.
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|| Logical OR.
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Unlike C, the result for a || b is one of the operands
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a, b rather than one of the numbers 0 and 1.
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a || b is equivalent to a ? a : b, i.e. if a tests as
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true, a is returned, otherwise b. The effect in a
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test like "if (a || b) ... " is the same as in C.
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&& Logical AND.
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Unlike C, the result for a && b is one of the operands
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a, b rather than one of the numbers 0 and 1.
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a && b is equivalent to a ? b : a, i.e. if a tests as
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true, b is returned, otherwise a. The effect in a
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test like "if (a && b) ... " is the same as in C.
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&& Logical AND.
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Unlike C, the result for a && b is one of the operands
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a, b rather than one of the numbers 0 and 1.
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a && b is equivalent to a ? b : a, i.e. if a tests as
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true, b is returned, otherwise a. The effect in a
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test like "if (a && b) ... " is the same as in C.
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== != <= >= < >
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Relations.
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== != <= >= < >
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Relations.
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+ -
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Binary plus and minus and unary plus and minus when applied to
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a first or only term.
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Binary plus and minus and unary plus and minus when applied to
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a first or only term.
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* / // %
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Multiply, divide, and modulo.
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Please Note: The '/' operator is a fractional divide,
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whereas the '//' is an integral divide. Thus think of '/'
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as division of real numbers, and think of '//' as division
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of integers (e.g., 8 / 3 is 8/3 whereas 8 // 3 is 2).
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The '%' is integral or fractional modulus (e.g., 11%4 is 3,
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and 10%pi() is ~0.575222).
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Multiply, divide, and modulo.
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Please Note: The '/' operator is a fractional divide,
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whereas the '//' is an integral divide. Thus think of '/'
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as division of real numbers, and think of '//' as division
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of integers (e.g., 8 / 3 is 8/3 whereas 8 // 3 is 2).
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The '%' is integral or fractional modulus (e.g., 11%4 is 3,
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and 10%pi() is ~0.575222).
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| Bitwise OR.
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In a | b, both a and b are to be real integers;
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the signs of a and b are ignored, i.e.
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a | b = abs(a) | abs(b) and the result will
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be a non-negative integer.
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| Bitwise OR.
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In a | b, both a and b are to be real integers;
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the signs of a and b are ignored, i.e.
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a | b = abs(a) | abs(b) and the result will
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be a non-negative integer.
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& Bitwise AND.
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In a & b, both a and b are to be real integers;
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the signs of a and b are ignored as for a | b.
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& Bitwise AND.
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In a & b, both a and b are to be real integers;
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the signs of a and b are ignored as for a | b.
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^ ** << >>
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Powers and shifts.
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The '^' and '**' are both exponentiation, e.g. 2^3
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returns 8, 2^-3 returns 0.125. Note that in a^b, if
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'a' == 0 and 'b' is real, then is must be >= 0 as well.
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Also 0^0 and 0**0 return the value 1.
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Powers and shifts.
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The '^' and '**' are both exponentiation, e.g. 2^3
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returns 8, 2^-3 returns 0.125. Note that in a^b, if
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'a' == 0 and 'b' is real, then is must be >= 0 as well.
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Also 0^0 and 0**0 return the value 1.
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For the shift operators both arguments are to be
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integers, or if the first is complex, it is to have
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integral real and imaginary parts. Changing the
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sign of the second argument reverses the shift, e.g.
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a >> -b = a << b. The result has the same sign as
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the first argument except that a nonzero value is
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reduced to zero by a sufficiently long shift to the
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right. These operators associate right to left,
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e.g. a << b ^ c = a << (b ^ c).
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For the shift operators both arguments are to be
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integers, or if the first is complex, it is to have
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integral real and imaginary parts. Changing the
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sign of the second argument reverses the shift, e.g.
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a >> -b = a << b. The result has the same sign as
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the first argument except that a nonzero value is
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reduced to zero by a sufficiently long shift to the
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right. These operators associate right to left,
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e.g. a << b ^ c = a << (b ^ c).
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+ - !
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Plus (+) and minus (-) have their usual meanings as unary
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prefix operators at this level of precedence when applied to
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other than a first or only term.
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Plus (+) and minus (-) have their usual meanings as unary
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prefix operators at this level of precedence when applied to
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other than a first or only term.
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As a prefix operator, '!' is the logical NOT: !a returns 0 if
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a tests as nonzero, and 1 if a tests as zero, i.e. it is
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equivalent to a ? 0 : 1. Be careful about
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using this as the first character of a top level command,
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since it is also used for executing shell commands.
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As a prefix operator, '!' is the logical NOT: !a returns 0 if
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a tests as nonzero, and 1 if a tests as zero, i.e. it is
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equivalent to a ? 0 : 1. Be careful about
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using this as the first character of a top level command,
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since it is also used for executing shell commands.
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As a postfix operator ! gives the factorial function, i.e.
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a! = fact(a).
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As a postfix operator ! gives the factorial function, i.e.
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a! = fact(a).
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++ --
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Pre or post incrementing or decrementing.
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These are applicable only to variables.
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++ --
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Pre or post incrementing or decrementing.
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These are applicable only to variables.
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[ ] [[ ]] . ( )
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Indexing, double-bracket indexing, element references,
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and function calls. Indexing can only be applied to matrices,
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element references can only be applied to objects, but
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double-bracket indexing can be applied to matrices, objects,
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or lists.
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[ ] [[ ]] . ( )
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Indexing, double-bracket indexing, element references,
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and function calls. Indexing can only be applied to matrices,
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element references can only be applied to objects, but
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double-bracket indexing can be applied to matrices, objects,
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or lists.
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variables constants . ( )
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These are variable names and constants, the special '.' symbol,
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or a parenthesized expression. Variable names begin with a
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letter, but then can contain letters, digits, or underscores.
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Constants are numbers in various formats, or strings inside
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either single or double quote marks.
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These are variable names and constants, the special '.' symbol,
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or a parenthesized expression. Variable names begin with a
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letter, but then can contain letters, digits, or underscores.
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Constants are numbers in various formats, or strings inside
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either single or double quote marks.
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The most significant difference from the order of precedence in
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C is that | and & have higher precedence than ==, +, -, *, / and %.
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For example, in C a == b | c * d is interpreted as:
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(a == b) | (c * d)
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(a == b) | (c * d)
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and calc it is:
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a == ((b | c) * d)
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a == ((b | c) * d)
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Most of the operators will accept any real or complex numbers
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as arguments. The exceptions are:
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/ // %
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Second argument must be nonzero.
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Second argument must be nonzero.
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^
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The exponent must be an integer. When raising zero
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to a power, the exponent must be non-negative.
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The exponent must be an integer. When raising zero
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to a power, the exponent must be non-negative.
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| &
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Both both arguments must be integers.
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Both both arguments must be integers.
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<< >>
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The shift amount must be an integer. The value being
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shifted must be an integer or a complex number with
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integral real and imaginary parts.
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<< >>
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The shift amount must be an integer. The value being
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shifted must be an integer or a complex number with
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integral real and imaginary parts.
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See the 'unexpected' help file for a list of unexpected
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@@ -217,7 +217,7 @@ operators
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##
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## Calc is distributed in the hope that it will be useful, but WITHOUT
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## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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## Public License for more details.
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##
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## A copy of version 2.1 of the GNU Lesser General Public License is
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@@ -225,8 +225,8 @@ operators
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## received a copy with calc; if not, write to Free Software Foundation, Inc.
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## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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##
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## Under source code control: 1991/07/21 04:37:23
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## File existed as early as: 1991
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## Under source code control: 1991/07/21 04:37:23
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## File existed as early as: 1991
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##
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## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
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## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
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## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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