Constant truncated to integer
floating-point, go, syntax-error
Solution
Replace
var c float64 = (-2.0 * math.Pi * k) / N
by
var c float64 = (-2.0 * math.Pi * float64(k)) / float64(N)
To quote the spec:
Conversions are required when different numeric types are mixed in an expression or assignment. For instance, int32 and int are not the same type even though they may have the same size on a particular architecture.
Go uses static typing and doesn't automatically convert between numeric types. The reason is probably to avoid some errors. For instance, what value and what type should `float64(2.5) * int(2)` yield? Should the result be `int(5)`? `int(4)`? `float64(5.0)`? In Go, this isn't an issue. The Go FAQ has more to say on this.
@jnml points out that, in this case, the following is enough:
var c float64 = -2 * math.Pi / float64(N)
Problem
The following GO program gives the error: ``` ./fft.go:13: constant -6.28319 truncated to integer ./fft.go:13: cannot use -7 * k / N (type int) as type float64 in assignment ``` Program: ``` package main import ( "math" "fmt" ) func main() { fmt.Println("Hello world ",math.E) var k, N int = 1, 10 var ans float64 = 0 var c float64 = (-2.0 * math.Pi * k) / N x := make([]float64,N) for i := 0; i < len(x); i++ { x[i] = 1 } ans = 0 for i := 0; i < N; i++ { ans += x[i] * math.E } fmt.Println(ans) } ``` Why cant I use an `int` in a type of `float64` ?